Second contribution, first story.
First I would like to say this IS a true story.
I was eighteen at the time, and I was home alone with my sister. My mom had just gone out and would be gone the entire day. I was getting ready for a shower and coming from my bedroom I passed my sister's room (14 years old at the time but hit puberty a lot faster than most girls), just a glance going by I realised she was totally nude, so I put my towel and clothes in the bathroom and quietly walked back to get a better look, I soon realised she was fingering herself.
I sat there watching her for about ten minutes and my cock was a rock. I was soon startled by my dog running through my living room chasing my cat and having looked away, when I turned back she was staring me in the face totally nude. She asked me why I was spying on her, lying I said I wasn't and I was going to have a shower. Meanwhile I couldn't stop staring at her chest. She asked me if I liked what I saw, lying I told her no, your my sister. She sees the bulge in my pants (I had totally forgotten about me having it) she replies with, well it looks like one part of you is enjoying yourself. I tried to make an excuse but my words just came out all wrong.
She could tell I was nervous and says its ok that I was watching her, she knew I was. I had a sort of confused expression on my face. She then grabbed my arm and pulled me towards her room and told me to rub her breasts. Holding and squeezing her breasts from behind with both hands she told me I was enjoying it. She could feel my cock pressing hard against her back through my shorts and on her bare ass, and then she told me to touch her pussy, without hesitating I did so, lightly thrusting my fingers into her while still with one hand rubbing her breast, abs and neck.
I could feel her wetness, it made me even more hard. I was already rock solid as she began to slowly ride my fingers as I thrust them into her. I could feel her ass massaging my cock sending me so close to orgasm. Then she suddenly stopped and took off my shorts and shirt(I normally go commando) and grabbed my penis which was at probably close to seven inches I was so aroused. She pushed me back on her bed and started to stroke me off. A good minute and I came big. She pulled me into the washroom and into the shower.
With her turning on the hot water quite hot made it all the more stimulating, she began jacking my penis again and after a couple of minutes I shot about five or six loads of small spurts onto her chest and one final large spurt onto the floor of the shower. Both of us soaking wet she pressed herself up against me and said thanks, it was good. I replied as was mine and gave her a kiss, and we both enjoyed the rest of the shower together.
To this day we still shower together, masturbate in front of each other and masturbate each other off when nobody is home. She is 18 now I am 21, no sex though, she wants to be a virgin as she marries, I am perfectly fine with that and what we do.
I hope my story gets through for people to read, thanks for reading.