When I was 18, I was engaged to a girl, also 18. Her parents wanted to break us up, so she left home and moved in with her friend's family. That situation was too restrictive, so my grandparents took her in. I worked nights and she worked days, so we only saw each other on weekends. I would stop and knock on her window at 2 am, on my way home from work, several times a week. She would let me in and we would have explosive sex in my grandparents' living room while they slept.
After she had been there about 2 months, my sexy 15 year old cousin, whom I have lusted after for years, also came to stay because of an unhappy home life. One night while my fiancée and I were heavily into foreplay, I teasingly said something to her about doing the same things to my cousin. To my surprise (and great excitement) my fiancée seemed very interested and encouraged me to go into the bedroom that the two of them shared and explore these things with my cousin. I got a little scared, saying that I couldn't because she was sleeping. Well, that just got my little darlin' even more excited, so what could I do...except comply.
We went into the bedroom and pulled the covers down. I slid my hands up my cousin's nightgown and caressed her tits and kissed her on the mouth and tits. My fiancée, meanwhile, was caressing her own tits. My cousin moaned and moved, scaring me, but I kept on. I slipped my cousin's panties down and fingered her pussy while stroking my dick. My fiancée, still caressing her tits, was starting to moan and thrash around. After getting my cousin's cunt juicy, I laid down on top of her and rubbed my dick against her wet pussy lips. She moaned some more but still did not wake up. My fiancée, by now was dipping her fingers inside her swollen cunt (this was a great turn on for me because until then she had only fucked in the missionary position and considered touching yourself or oral sex "dirty"). I still was kind of scared about what I was doing to my cousin, but was so turned on by it and what my fiancée was doing, that I decided What the hell? and slid my swollen dick into my cousin's very wet pussy. I know for a fact that she was a virgin until that night, but I slid in with no problem because she was so wet. I pumped for about 10 minutes and then shot my steaming load into her.
I pulled up her panties, straightened her nightgown and went over to my fiancée. She licked my and my cousin's cum off my dick and I licked up the sticky mess she made on her own pussy. My cousin has never said a word about that night, but I have always wondered how someone could sleep through all of that. I suspect that she not only enjoyed what I did to her, but she also was secretly watching what my fiancée was doing to herself. Some day maybe I'll have the nerve to ask her about it.