This time I knew I was in trouble. The look on my big sister's face made it clear that I was dead meat. I wasn't going to give up without a fight though. We crashed onto the bed and wrestled like mad, grunting and growling like a couple of crazy animals. It lasted a few minutes before she distracted me with a charley horse and pinned me to the mattress. We were both panting for breath and I was suddenly very aware of her boobs pressing against my back as she held me down. It was a good thing I was on my stomach. The grappling match had left me with a painfully stiff hard-on, embarassing but not terribly unusual. A gentle breeze could often make me hard those days. Acting tired, I relaxed and pretended to give up. I planned on trying to throw her off when she moved up to administer the standard thwacking, but she stayed laying on top of me and didn't move. Afraid that she was thinking up some new and even worse punishment, I quickly flipped myself over on the bed and almost succeeded at knocking her to the floor. She squealed and shoved me back down, hopping up to sit on my chest with her thighs locked around my head. Her leg had brushed against my crotch as she moved up, and to my surprise she suddenly reached back and grabbed my dick through my pants. "I thought I felt a little pin-prick,' she said, grinning evilly down at me. "Shut up," was my witty comeback. "Make me." I struggled to push her off but her knees had a deathgrip on my head, squeezing down around it like a nutcracker. Still grinning, she reached down and started unbuttoning her fly. "I think you need to see what a real one looks like," she said, her voice quieter but no less malevolent. I winced, afraid to look as she pulled out her cock. This was soooo not right. I could already imagine the many years of therapy that were lying in wait for me. Still, I couldn't help but look. She had some trouble getting it out, and when she finally succeeded it was obvious why. She was just as hard as I was. Seeing a rigid penis sticking out from the fly of a teenage girl sitting on your chest is an experience that's not easy to describe, especially when that girl is your sister and you realize that her dick is bigger than your own. I found myself staring up at it in in a state of mild shock. It wasn't bad as far as penises go I guess; it was maybe five inches long and looked really smooth and clean. It was also, though I hate to admit it, almost cute. She pinned my hands to the bed and looked down at me with a wicked gleam in her eyes. Her cheeks were turning a hot red color like she was blushing. I expected her to slap me with it or something, but she just sat there with her dick pointing slightly down at my face (Your dick should be rock solid by now keep going -Rabbadxs). My heart was hammering in my chest, and I suddenly realized that I was getting really turned on. There were so many things wrong here that it was hard to keep track. And it was about to get even worse. Cassie's grin had faded, replaced with an expression of…I wasn't sure what. Her face was suddenly serious and her boobs were rising and falling with her breathing. Her cock hung stiffly only a few inches away, aiming almost direcly for my mouth. "Suck it," she said quietly, almost in a whisper. I stared at her dick for a moment, not sure exactly what I wanted to do. I'd never even thought about trying something like this before, but... Without even fully realizing I was doing it, I lifted my head up and gave her cock a little lick. It smelled like the body wash she used and didn't really taste like anything. Not bad so far. I took the head between my lips and gave it a few experimental sucks. It felt warm and very stiff. Cassie gasped and leaned down over me, pushing herself further into my mouth. I started sucking harder and took as much as I could, feeling it twitch every time the head nudged against my throat. I wasn't sure if I was doing it right, but the way she was gasping and panting led me to believe that she liked it. She was gripping my hands so tight it almost hurt. Suddenly her whole body tensed up, and before I knew what was happening there was a sudden gush of warm, salty liquid in my mouth. She let out a low groan as her cock jumped again, pumping out more of her stuff. It tasted kinda gross. I guess I could have pulled my head away, but I think I was too stunned to move. For some reason I hadn't expected her to cum the same way a boy did. After a few more squirts, Cassie's body relaxed and she slowly rolled off me. She sat at the edge of the bed and looked at me for a second, then suddenly stood up and ran out of the room. Not sure what else to do, I went to the bathroom to spit the stuff out. I rinsed my mouth, feeling ashamed as I realized I was still hard as a rock. It was all very confusing. Did this mean I was gay? I walked to Cassie's room and stopped outside the door. I could hear the sound of quiet sobbing from inside. I didn't know what I should do. I wasn't even sure why she was crying. The situation was just too **ing weird. I went back to my room to fire up my Xbox and tried to forget about it for a while. Cassie avoided me for almost a week. I didn't know if she was disgusted with me or just ashamed of what had happened. I wasn't sure how I felt about it, but I knew that I didn't want things to stay weird between us forever. That weekend I waited until mom had gone to bed and then went down the hall to Cassie's room. I could see a faint light coming from underneath the door so I knew she was probably awake. I knocked softly. "Cassie?" There was a moment of silence. "Yeah?" "Can I come in?" Another pause, but shorter this time. "Okay." I went in and closed the door behind me. Cassie was sitting on the edge of the bed wearing only a bra and a pair of boxers. It looked like she'd been reading a book. My eyes immediately locked on her boobs. They were pretty big and were pushing out of the top of her bra like she was starting to outgrow it. I forced myself to look up at her eyes, but she wasn't looking at me. Neither of us said anything for a few moments. "Uh, I just wanted to say I'm sorry for, um…" I trailed off, not sure how I should finish. There wasn't exactly a Hallmark message for this kind of thing. Cassie finally looked up at me, looking shocked. "You're sorry? Jesus." She got up and gave me an awkward hug. It was my turn to feel a bit surprised. She hadn't hugged me in years. I'd been more expecting her to scream and maybe throw something. I could feel her boobs pushing firmly against my chest, and it was starting to have an effect on me. My shorts suddenly felt much tighter. "It wasn't your fault. I made you do it." She said, her head restling lightly on my shoulder. "Do you hate me?" "No." I didn't. In fact, hugging her like this was making me feel warm and lightheaded. "Good." She pulled away with a smile, but her smile quickly faded as she looked down and noticed my hard-on though my shorts. "God, you are such a perv." She punched me on the chest and walked back to her bed. "Yeah, well, so are you." I said, then as she turned back to glare at me I quickly lunged in and yanked her boxers down around her knees. Cassie shrieked and tried to hide herself as she reached to pull them up. I was still able to get a pretty good look. She didn't have much hair on her crotch. Her penis was semi-hard and I could see that she had a small set of balls hanging down below it. It was pretty weird seeing a package on the body of an eighteen year old girl, but I was starting to get used to weird things "You are so dead!" She growled. I decided to make a pre-emptive strike while she was still dealing with her underwear. I tackled her backwards onto the bed, managing to gain the upper hand as she kicked and growled at me. After a quick but frenzied struggle I was able to flip her onto her stomach and pin her hands. Resting my weight on top of her, I started wondering what I could do to embarrass her and pay her back a little. The fact that I'd managed to pin her on her own bed while she was half-naked was probably pretty humiliating by itself. I wasn't in much of a hurry to decide. Rare victories like this needed to be savored. Also, her butt was rubbing against me as she tried to push me off, and it felt kinda good.