Note: This story was dynamically reformatted for online reading convenience. >Little Sister's Amazing Underboob by IronBuddah Copyright(C) 2021 by IronBuddah Prologue A family member spraining their ankle doesn -(TM)t usually change much in your life. They limp or hop around for a few days; maybe you go get something for them so they can stay in their chair. Maybe they use an ice pack or heating pad for a while. All and all, no big deal. However, when our mother sprained her ankle on the first day of a family camping and hiking trip, it had a huge impact on my sister and me. What kind of impact? Well, if I say now, I won -(TM)t have much of a story to tell. But it was pretty major, especially for two teens. Mom had sprained her ankle Friday night by stepping on a rock in the dark. We had planned on going on a family hike Saturday. We got an extra bag of ice for the cooler since we were making ice packs for Mom that night. Her goal was to ice it heavily so she could still hike the next day. We took our time making breakfast so that Mom would have a chance to ice the ankle again before we headed out. However, even after resting and icing it the night before, and icing it again this morning, Mom decided she just wasn -(TM)t up to hiking. Our Dad told us, -Mike and Tanya, why don -(TM)t you two head out. I -(TM)ll stay with your Mom around camp. - -I can stay with Mom, - Tanya volunteered. -No, I -(TM)ll stay; you go hike with your brother, - our Father replied. Now at the time, I -(TM)d have rather gone hiking with my Dad, but I wouldn -(TM)t have had nearly as much fun. Is that enough of a hint about what happened while hiking with my sister? Chapter 1: First Feel Tanya and I were walking one of the main trails out of the campsite, and while it wasn -(TM)t crowded, there were plenty of people we could see either in front of us or behind us. When we came to a sign, Tanya said, -Let -(TM)s do this trail! - I looked at the sign, and checked the trail map. It was rated at maximum difficulty in the guide. -Are you sure sis? It says here that you gain thirty-five hundred feet over a four mile hike. - -We -(TM)re both in shape; it should be fun. I wouldn -(TM)t have suggested it if Mom & Dad were with us, and that -(TM)s before she sprained her ankle, but just the two of us, why not? - At that point I just shrugged. No point in getting chewed out when we got back to the campsite that night for arguing with my little sister. After about 5 minutes, it became clear that no one else camping and hiking that weekend was thinking the same way Tanya did; we were all alone on the trail. Tanya realized the same thing. -Here, hold my backpack for a second. I -(TM)m going to change shirts. Turn around and take some pictures or something. - -Really? - -Yes, really, I want to wear something a bit more comfortable. - -Fine. - I got the good camera out and looked for something interesting to take a picture of. I hated to admit it, but Tanya -(TM)s choice of a route should provide some great views once we reached the top of the trail. In the meantime, I went looking for some birds or squires I could snap a picture of. I -(TM)d change lenses when we got to the top for a wide angle lens, but I was better off finding something specific to take a picture of at the moment. When Tanya told me to turn around I was stunned. I guess technically what she was wearing would have to be called a crop top, but it was more like half of a crop top it was so short. It was also obvious that she had taken her bra off as well. Hell, I could see the undersides of her boobs it was so short. I blurted out, -Damn Tanya, where the hell did those come from? - -I keep -~em squashed under a sports bra all the time. Since we -(TM)re obviously the only two people on this trail I thought I would set the girls free. - -They -(TM)re free all right! I bet I could see your nipples if you lifted your arms over your head. - -You would not! - -I -(TM)m going to tell Mom & Dad you got half naked on the hiking trail. - -Oh don -(TM)t be so dramatic. There -(TM)s nothing wrong with this top. Look, I -(TM)ll show you. - With that Tanya lifted her arms over her head and while I could see a lot more of her tit flesh now, her nipples did not come into view. Even though this was my little sister, my heart started to race from what I was seeing. Tanya had the most amazing underboob showing that I had ever seen in any sort of pinup picture or porn video. At was at this point a crazy idea entered my head. It might get me slapped and then grounded for life and probably shipped off to military school on top of it all, but for a horny teen boy, it seemed like a good risk to take. Before I had it all planned out, I asked Tanya, -Would you have worn that shirt if Mom & Dad were hiking with us? - -No... - -Why did you even have it with you then ... never mind ... let me touch them and I won -(TM)t say anything to our parents about your choice of hiking clothes. - -What? You -(TM)re my brother; that -(TM)s weird! - -Maybe so, but that -(TM)s my offer, - I countered hoping for the best. Tanya stared at me, -I can -(TM)t believe ... fine, but you can only touch what -(TM)s showing from under the shirt. - -Oh man! - Why did I say that? Tanya knew she had the upper hand now in this strange sibling negotiation. -If my shirt is obscene as you seem to think it is, that should be plenty for you. And, you can only touch them for ten seconds! - -A minute, - I countered. -Twenty seconds. - -Forty-five - -Half a minute, that -(TM)s my final offer. - -Fine, - I accepted before she had a chance to change her mind and back out of the deal. With my hands twitching, I stepped closer to Tanya and asked, -So how should I... - -Calm down you perverted horn dog! Let me get a timer set. Gee, you are all up in my personal space! - -I kind of need to be for our deal to work don -(TM)t I? - -I guess. Ready? three, two, one, go! - I may have jumped the gun a bit, but Tanya seemed to be expecting that. I touched my sister -(TM)s breasts gently, almost tentatively. They were so soft, and kind of heavy. I gently cupped and squeezed them. I became almost instantly hard for my sister, and my eyes were locked onto the front of her skimpy shirt. I was fascinated by the way her breasts moved in response to my touch. I felt like I had just reached out to touch Tanya -(TM)s tits when the beeper on her phone started going off. How had thirty seconds passed so quickly? I didn -(TM)t pull my hands away and Tanya didn -(TM)t say anything. I was still gently feeling and lifting Tanya -(TM)s large breasts. As her phone -(TM)s alarm tone continued to sound, I became a bit bolder and reached up under the shirt a bit to get a better feel for her full breasts. -Oh wow! - I sighed. -OK, that -(TM)s enough, - Tanya said as she stepped away from me. -You should be happy, I nearly let you go a minute anyway. - -Why didn -(TM)t you stop me as soon as the alarm went off? - I wondered. -You have a gentle touch. I -(TM)ve let a few dates get to second base, and they were anything but gentle. One squashed them way worse than a sports bra and another seemed like he was trying to spin a top the way he attacked my nipples. - I almost groaned when she said that. I hated hearing that my sister had been felt up by other guys when I never had gotten more than a good night kiss on the cheek. -Oh, don -(TM)t go making it weird after I said you had good boob handling technique. We -(TM)ve got a deal and you got your payment, so I had better not hear a word about any of this to either parent! - Chapter 2: Free Balling -Damn, Sis, how big are those things anyway? - -You were just feeling me up; you should know how big they are. - -I mean, what size bra do you wear? - -32DD - I groaned again. How had I never noticed that my skinny little sister was some sort of slim and stacked titty goddess? I was so hard and horny after getting my first chance to touch someone -(TM)s breasts. At this point I didn -(TM)t care that they were my sister -(TM)s because they were absolutely amazing! -I said don -(TM)t go making this weird. Let -(TM)s get back to hiking. - I tried to get back into the mindset I had when we got on this trail; that we were going to have to work hard to do the 4 miles in a reasonable amount of time. However, I simply couldn -(TM)t stop thinking about Tanya -(TM)s tits. I wanted to touch them again, I wanted to stare at them, and I was quickly becoming obsessed with what my sister would look like topless! It probably wasn -(TM)t surprising then that I kept stopping and looking behind me to see how Tanya was faring on the trail. It really hadn -(TM)t gotten steep yet, so neither of us was having to work that hard. -Dude! Why do you keep stopping? We -(TM)re never going to make it to the top of the hill at this rate. - I was probably too obvious in my inability to look at anything but the exposed undersides of Tanya -(TM)s breasts because then she added, -Are you stopping to check out my rack? I told you not to make this weird! Give me the map; I -(TM)m taking the lead. - As I handed the trail map over to Tanya and she moved in front of me, I heard her mutter under her breath, -At least he -(TM)ll be well motivated to follow me! - My sister had sized up the situation correctly. I have always found tits to be more interesting than asses, but there was something enticing about my sister -(TM)s narrow waist and swaying hips as I followed her. Pretty soon, as the trail became steeper, the way the muscles in her butt flexed as she moved added a new dimension to my fascination with my sister -(TM)s body. My cock ached with desire for Tanya and I really wished I could take a break from hiking and rub one out. I was insanely horny after feeling my little sister up, and that -(TM)s the only explanation I have for my next decision. If Tanya could walk the trail with her tits hanging out, why couldn -(TM)t I free my aching cock from my shorts? I couldn -(TM)t think of a good reason not to do just that, so I quietly unzipped my shorts and fished my half hard cock out into the open. As we walked, my exposed cock got harder and harder, and pretty soon I was walking down the trail with a raging boner pointed straight at my own sister -(TM)s ass. My brain warred against itself as I sought to balance not getting busted with my hard pecker out in the open, and the amazing way it felt to have my raging boner free from my shorts so it could swell to full hardness in honor of my sister -(TM)s sexy body. It felt like I only had it out for two or three minutes, and that I would have plenty of time to zip it back up before Tanya busted me exposing myself. However, the next thing I knew Tanya stopped and announced, -There -(TM)s the one mile marker. - Then she turned around, -What? Mike, what the fuck are you doing? - I decided there was no point in acting like I was ashamed, although inside I was terrified. -Hey, if you can set your tits free, why can -(TM)t I set my cock free? - I hoped that sounded more confident than I felt. -Damn Dude! At worst I look a little trashy; you look like some sort of giant pervert. Put that thing away! - Well, my sister -(TM)s initial reaction to seeing my hard on could have been worse. It was then that I discovered the fishing a half hard cock out of your shorts was a lot easier then putting a fully hard cock away. For one thing, it felt amazing to touch it after what had to be at least ten minutes of hardness, if not fifteen. Then there was the fact that something this hard and this stiff couldn -(TM)t simply be stuffed back in. I had to unbutton and unzip my shorts to have any chance of getting it contained again. On top of all that, even after I had it under my clothes again, I was so hard that my swollen cock head stuck out above the waistband of my shorts throbbing angrily. Shaking her head, Tanya wondered, -Why didn -(TM)t Dad accept my offer to stay with Mom today? - Addressing me directly again, -What is wrong with you Mike? In what universe is hiking with a big boner throbbing for anyone to see a good idea? - -I don -(TM)t know, - I admitted. -I just got so horny after feeling you up that it seemed like a good idea to take it out, and then once it was out, it felt so good to be that hard that I kept delaying putting it away. You know how they say time flies when you -(TM)re having fun? I felt like I took it out only two or three minutes ago, but we must have walked half a mile with me enjoying that wonderful hard on! - -Half a mile? Seriously? I walked half a mile with my brother pointing a boner at my ass? I can -(TM)t believe you -(TM)re older than me and did something like that. - -Hey, it could have been worse, the mesmerizing sway of your hips could have caused me to blow my load on you. - Mouth open and staring at me in disbelief Tanya finally spoke, -Why would you tell me that? I -(TM)m your sister. Shut up, just shut the fuck up! - Chapter 3: Second Feel -Damn it, I know I just told you to shut up, but what -(TM)s it going to take to make you promise not to do that again? - -Seriously? - -Yes seriously! Why would I have prefaced that with -~I know I just told you to shut up, -(TM) if I weren -(TM)t serious. - -Well, if you let me touch your tits again, I promise I won -(TM)t whip it out again before mile two. - Tanya looked like she was going to object but then said, -Fine, whatever it takes to get you to behave. Sheesh, you act like you -(TM)ve never touched a girl -(TM)s chest before. - I didn -(TM)t say anything, but Tanya could tell just by looking at me, -Son of a bitch, I -(TM)m the first person you -(TM)ve felt up, aren -(TM)t I? Damn it, the first tits you ever touch belong to your own sister. You -(TM)re not going to be able to help yourself when it comes to not making this weird are you? - -I don -(TM)t know what to say; your rack is amazing! - I stated while reaching out to cop another feel. -Hey, you don -(TM)t get your reward until after we get to the mile two marker! - Tanya snapped while slapping my hands away from her fantastic boobs. I moaned in frustration, and Tanya stomped off down the trail. I could hear her muttering, -Fuck, fuck, fuck! This is so fucking weird! - I was so entranced by the way Tanya -(TM)s body moved and the promise of another chance to touch the bare skin of her tits that I hardly noticed the trail becoming more difficult. I also hardly noticed the passage of time. Only when Tanya announced that we had reached the mile two marker did I realize I was huffing and puffing and dripping with sweat. I looked down at my watch. It was 11:30, and the guide had said to alott 3-4 hours to walk the trail one way. We had covered half of it in an hour! Then I looked at Tanya and saw that she too was dripping sweat. Of course I was looking at her tits, and I noticed a bead of sweat hanging from the underside of one of her magnificent boobs. I reached out and collected the drop of sweat on the tip of my finger, then I put it into my mouth. It didn -(TM)t taste like much, just a bit of salt, the same as I could taste from my own sweat. However, between the slight touch of Tanya -(TM)s breast and knowing where that drop of sweat came from, I was hornier than ever. Tanya palmed her face in her hand saying, -Why do you insist on making everything as weird as it could possibly fucking be? - She didn -(TM)t wait for a response before adding. -I was going to let you feel me up now, but after that stunt I -(TM)m going to make you wait until after we eat lunch. - We pulled the lunch we had packed and ate in silence. It wasn -(TM)t like I could carry on a conversation about much beyond how sexy I had discovered my little sister to be or how much I was looking forward to touching her tits again anyway. All in all, eating in silence was probably for the best. I practically inhaled my food and washed it down with some water from a canteen. Then I ogled Tanya as she ate loving every bounce and jiggle of her large tits. I practically held my breath when she finished and jumped up when she said, -OK, you get another thirty seconds. - My fingers were twitching and I was panting as I watched Tanya get her phone out. She gave me a countdown, -Three, two, one. - Then those amazing tits of hers were in my hands again. I tried to be as gentle as I was the first time even though I was bursting with excitement. I think I succeeded on the gentleness front, but I couldn -(TM)t keep my fingers to just the portion of Tanya -(TM)s breasts hanging out under the tiny crop top. I was reaching up under the shirt and filling more and more of my hands with her large breasts and she wasn -(TM)t stopping me. My heart was pounding, and I could feel every heartbeat in my rock hard cock. Far too soon for my liking, I heard Tanya -(TM)s cell phone start beeping again. Just like the first time though, I didn -(TM)t pull my hands away. Since I was already well under her shirt, I decided it was worth the risk to try to touch Tanya -(TM)s nipples. I didn -(TM)t move suddenly, but started subtly trying to reposition my hands. I didn -(TM)t know it at the time, but Tanya was biting her lip and that was a sign that she was enjoying what I was doing. However, it made me nervous that she was about to stop me at the time. So I rotated my hands again and found Tanya -(TM)s nipples with my thumbs and started rubbing them. She bit down on more of her lip, and I could feel the little nubs growing harder at my touch, but then she stepped back saying, -OK, that -(TM)s enough. I keep letting you get more than your thirty seconds. - -I -(TM)ll take as much of that as I can get, - I admitted breathlessly. I could see Tanya -(TM)s hard nipples trying to poke through the fabric of her shirt. It made an amazing sight even better. -You do realize that I -(TM)m your sister and this whole situation is pretty fucked up? The only reason I -(TM)m letting you do this is that we -(TM)re on this isolated trail. - -Well, I -(TM)m glad you wanted to hike it then. This is the most amazing thing that has ever happened to me! - Tanya sighed, -Making it weird again. - -I can -(TM)t help it, I -(TM)m enthusiastic when it comes to your big tits little sis! - -Dude, dude! Why do you keep saying things like that? - -Hey, can I make it weirder? - Looking at me with disbelief Tanya couldn -(TM)t even speak. -We need a new bargain to keep me well behaved until mile three. - -Let me guess, you want to feel me up again. - -I was actually thinking about kissing you. I couldn -(TM)t take my eyes off your lips when I was feeling you up this time. - Tanya -(TM)s eyes got wide, but she agreed, -Fine, if that -(TM)s what it takes to keep your cock in your pants, you can kiss your sister at mile three. - -On the lips, - I stipulated. I didn -(TM)t want to admit that would also be the first time I was kissing a girl on the lips. -Fine, one kiss on the lips at mile three. And you don -(TM)t get to feel me up while you -(TM)re doing it either. - Damn and double damn, I hadn -(TM)t struck a good bargain at all! I should have asked for a time limit on kissing and at least one hand on a tit. Well, I could try for one really long kiss at least. Chapter 4: Making Out The trail grew steeper still, and my desire to kiss Tanya certainly helped keep me moving. This isn -(TM)t to say that I moved uphill without resting and encouraged Tanya to do the same. We both stopped to rest a few times and take a swig of water from our canteens. By the time we saw the three mile marker we were both dripping with sweat and a little bit out of breath. In shape or not, this was a strenuous trail and we weren -(TM)t taking it easy. I stepped closer to Tanya wanting to claim my kiss, but she held a hand up to keep me away saying, -Wipe your face off, I don -(TM)t want you dripping sweat on me. - As I toweled my face off with my shirt I responded, -What about you? You -(TM)re sweating as much as I am. - -Well, you seem to think it -(TM)s sexy, or at least not gross. - I actually did think it was sexy. The beads of sweat on Tanya -(TM)s face were cute, and the ones dripping from her big boobs made me ache with desire for my sister. On top of that, her shirt was clinging to her chest, and I could see more underboob than I had even when Tanya lifted her arms over her head. I almost jumped to Tanya when she motioned that I could approach for the promised kiss. Mindful of Tanya -(TM)s stipulation that I couldn -(TM)t touch her chest while kissing her, I put one hand on the small of her back and the other behind her neck as I slowly dipped her body and moved my face closer to hers. Despite the thought I had a mile back when Tanya had agreed to let me kiss her, I was approaching this kiss very gingerly. I didn -(TM)t do anything to try for a long drawn out kiss either. Actually, as our faces got closer and closer, I just barely touched my lips to Tanya -(TM)s and then pulled back to look at my sister. -Dude! That kiss sucked! - Tanya scolded me. -How do you ever expect to get a second date if you kiss like that? Try this! - My little sister grabbed my face with both hands and pulled it back down to hers. Then my brain almost exploded as I felt her tongue enter my mouth. Now I was French kissing my sister and I had no idea what I was supposed to be doing. At first I tried to keep my tongue out of her way so she could put hers wherever she wanted. She seemed to be pulling my face more intensely to hers and her tongue seemed to be seeking mine out, so I stopped trying to evade hers. At some point instinct kicked in, and I started moving my tongue not to evade hers, but somehow complement what she was doing. That finally seemed to make Tanya happy because she relaxed in my arms as our tongues dueled. When the kiss finally ended, Tanya stated, -You finally started catching on at the end. Please tell me you don -(TM)t kiss your dates the way you kissed me at first. - When I didn -(TM)t answer immediately Tanya continued, -Aw fuck! Your first kiss ever was with me, wasn -(TM)t it? Damn it! I can -(TM)t believe I -(TM)m saying this, but you need more practice kissing. I can -(TM)t have my big brother blow a bunch of dates because he doesn -(TM)t know how to kiss a girl. - My brain was still trying to process my good luck when I felt Tanya -(TM)s hands on my face and her tongue in my mouth again. I knew Tanya had said I wasn -(TM)t allowed to do this, but I couldn -(TM)t help myself. I removed my hand from the small of her back and grabbed one of her magnificent tits. I didn -(TM)t even try to avoid her nipples although I tried to keep my touch to the gentle since she really seemed to like that. Tanya didn -(TM)t protest, and in fact threw her hands around my neck so she could continue to support herself. That encouraged me to tug her shirt out of the way and start feeling one of her bare tits up. I wanted to see what I was playing with, but that would mean breaking the kiss with my sister. I kept kissing Tanya since that seemed to be the more urgent of my two desires. Damn! I thought I had been horny before, but making out with a girl at the same time I was feeling her up was dialing my horniness up to eleven. I twisted my body so that Tanya was bound to be able to tell that I was hard, but that didn -(TM)t seem to bother her either. It was another instinctive reaction. Tanya was making my cock hard and feel amazing, so it was only natural that I would want to rub it against her slim body. Finally breaking the kiss, Tanya gasped, -I -(TM)m going to have to be careful, I was just going to give you a chance to practice kissing a bit more, but those gentle hands of yours have got me wanting to make out. - Not needing any more encouragement than that, I squeezed on Tanya -(TM)s exposed tit a bit more and brought my mouth back to hers. She pressed her lips to mine eagerly and once again our tongues were dueling. If there had been a bed or couch handy I -(TM)m pretty sure I -(TM)d have tried to lay Tanya down and have sex with her. However on the steep mountain trail we stayed standing and kept kissing feverishly. I guess all good things have to come to an end because Tanya broke the kiss and said, -Enough, there -(TM)s only so much making out siblings should do. If we keep this up I -(TM)m going to end up as horny as you obviously are already. - As Tanya stepped away from me, I saw the most amazing thing. She hadn -(TM)t pulled her crop top down over the tit I had been feeling up. I got a clear, close up, unobstructed view of that marvelous jug! My mouth had already been hanging open from the kissing but now my jaw really dropped. I immediately forgot my sister -(TM)s words trying to slurp Tanya -(TM)s delectable nipple into my mouth. Stepping back and giggling Tanya covered back up. -Now now, you need something to motivate you to behave on the way to the scenic lookout. - Then she trotted off down the trail. Had my little sister really just promised me a chance to suck on her titties? It certainly seemed like it! I hurried down the trail hardly able to contain myself.