Sex with the Girlfriends Sister

So this true story started with a long weekend away to the lake, myself, girlfriend & her sister went away to the lake for a June long weekend.

The weather was fantastic, hot & sunny, so we decided to take a boat trip on the lake we was staying on.

The boat had a bar & as I was on holiday I thought about starting early around 11:00 in the morning. I got some drinks & my girlfriend sister was not to happy but said thank you & we enjoyed ourselves with a few more trips to the bar.

When we wanted to land we went to a restaurant and had an early meal, we kept on drinking, by now we was pretty much drunk, and got onto some stronger drinks. We started to walk back to the place we rented & took drinks with us. My girlfriend really needed to go to the toilet so walked ahead while I helped her sister walk home, who by this stage was very drunk.

I have fancied my girlfriends sister for a while and thought "what she would be like in bed", but I knew she did not want to have sex with me. We got back to the house & my girlfriend is still in the bathroom, I put her sister on top of the bed who is laughing, I say to her to shut up or I will kiss her, she laughed & I kissed her for the 1st time. She returned the kiss & I started to think that I might be able to get something out of her.

I kiss her again but I put my tongue in her & she does not force me away. I put my hand on her left breast & she let out a little moan. This was it, I'm shagging the sister I thought. My girlfriend came out of the bathroom & she said she was going to bed as was totally pissed. I jokingly said I was going to sleep with her sister then to which she said ok..

I went to the bathroom & when I came out my girlfriend sister had almost fallen asleep, but I was pretty hard & determined to have sex with her, I went back & kissed her until she woke up, I removed her top & sucked her left nipple. She woke up & said what was I doing? I replied with that my girlfriend said it was ok, she relaxed & let me carry on and eventually her legs started to open, she had a dress on so was easy to put my hand up and push her knickers to one side.

I knew I had no condoms as me and my girlfriend don't use them now, I did not know if she was on any birth control but I did not care, My dick was throbbing even before I get in her. I said to her I was going in but by then she had fallen back to asleep. I thought I should stop but I was so ready & I knew I would probably never get this chance again. I pushed my dick in & started to move up & down on her. I was actually happy she fell asleep as I was not going to last very long, and probably would of been disappointed. I was now ready to cum and was really thinking about pulling out but again I thought I might never get this opportunity again, so I cummed in her. I could not believe it, I had cummed inside my girlfriend's sister pussy.

After I cummed in her, I got off her, I put her knickers back in place, knowing they would have some of my cum in them as it dribbles out. I then went and got into my bed next to my now sleeping girlfriend, my girlfriend not knowing I just had unprotected sex with her sister.

A few hours later we woke up with some very sore heads, my girlfriend who is always quite horny decided to get on top on me, she said sorry for not being horny last night & for going straight to sleep but she was pretty drunk. We had sex right then. I kept on thinking that just some 6 hours earlier I was actually having sex with her sister and I had not washed my dick. I still could feel her sister on me and now my girlfriend was adding to that feeling.

As we was having sex, I heard the girlfriends sister get up & went to the bathroom, I was panicking, thinking any second she going to know what I did from the mess in her knickers, but nothing happened. We had breakfast and were talking about the previous night and what a laugh it was and we drunk far to much. Thankfully she said that she could not remember anything after all the drink. I breathed a massive sigh of relief as I now knew she would not say anything to my girlfriend about it.

Secretly I'm hoping next summer we go away again so I can try and have sex with her again. I still don't know if she was on birth control but luckily nothing happened. Every time I how have sex with my girlfriend I always think of that night in June and she sisters lovely shaved, clean pussy.