3 years ago my parents went away and left me at home in charge of my 19 year old sister. On the second day they were away my sister invited a load of people round for a house party and I was told to keep out of the way which I did by staying in my room.
At about 1 am it was quiet so I guessed everyone had gone I decided to go down for a drink, as I got onto the landing at the top of the stairs I could hear some people so looked down into the lounge. I saw my sister clearly passed out on the sofa with a guy fucking her while another guy was watching and laughing. After a few minutes the guy got off and took off his condom and dropped it on the floor, then the second guy fucked Gill while the first guy drank a beer. I know it was wrong but I got hard and even started stroking.
Pretty soon this guy also finished and dropped his condom on the floor then they both left after picking up a few cans of beer.
I went down stairs and stood looking at my sister laying there with her pussy exposed and whacking off. Then I though well these 2 guys have fucked her why shouldn't I. I got on top of her and fucked her while she lay there I admit it was not so long before I shot my cum in her.
In the morning I came down and Gill was just waking up she was still naked laying there, she screamed at me to get out but I stood there and told her I had seen her fucking with 2 guys last night, I did not mention that she was passed out and I showed her the condoms on the floor. LOL the look on her face then as she realised what I had seen, she begged me not to say anything and asked me who the guys were as she couldnt remember.
I never told her that I had also fucked her though