Note : This story is complete fictional : never try to do it in real live! It was Friday and I had just been asked if I could look after my next door neighbours children for a couple of days as their parents were going a way for the weekend. I was only 17 at the time but nevertheless accepted. I was left to look after abbey who was 15 and Elizabeth who was 13. I was told I could sleep in their parents bedroom and the girls could not be in bed any later than 10. Late Friday night I was going up stair and one of the girls was in the shower. There was a slight slit through the door from which I could see abbey, with her nice 34C tits and her tight little shaven pussy. As I was watching I suddenly saw Abbey slide her hand down her body and starting to finger herself. I could feel my 8-inch dick beginning to rise. Being careful I made sure her younger sister Elizabeth was downstairs, then took out my dick and started to masturbate. A couple of minutes later Abbey turned off the shower and put a towel round her, at this point I was just about to blow my load. Luckily abbey began to get dressed in the bathroom, but as I was blowing my load over the bathroom door I could hear Elizabeth coming up the stairs. After hearing this I quickly rushed in to my room forgetting to clean my load off the door. I stayed in my room until it was 10 and then told the girls to get ready for bed. As they were doing that I went to clean off the bathroom door, but to my surprise someone had already cleaned it up. Once the girls were in bed I went to check on them , and Elizabeth, the younger one told me to come in her room and close the door. As I did this she said, "I saw you spying on my sister in the shower." at this point I couldn't really say much and I tried to deny it until she said, "I saw you blow your load all over the door". Again I tried to deny but she began to blackmail me, "I licked the door off for you and in return I want you to fuck me" "No I can't do that your only 18 years old" I said but she then told me she had being playing around with her dads video camera and had it all on tape. At this point she began to unzip my jeans, Elizabeth took off all my clothes and started to stroke my dick, my dick couldn't stand it anymore and rose to attention. At this point Elizabeth took off her silk pyjamas to reveal a lovely pubeless tight pussy and some lovely small tits. Elizabeth lay me down on her bed and started to suck on my dick, she swirled her tongue round and round the head of my dick and bought me to the point where I could blow at any second. Suddenly Elizabeth stopped and said she wanted me to lick her, as I did she began to moan, louder and louder, and screamed "I want you to Fuck me!" I then had to remind her, her sister was in the next room. I did as she wished to make sure that the video never got in to the wrong hands but as I began to slip my penis in to her slit her sister walks in. "What are you doing to my little sister you pervert!" she screamed but was soon silenced as her little sister told her that she had a video of her fucking some boy from school and would show it to mum and dad unless she would join in. Abbey agreed and took off her nightgown to reveal her wearing a black thong that was too small for her. Elizabeth took my dick out her young cunt and went over to her sister and gave her a full on kiss, she then started to play with abbeys tits then slowly sliped down her thong to reveal a tight shaven pussy. She started to play with her sister pussy and ordered her sister to touch her all over while I fucked her. This was a dream come true, 2 beautiful sisters that I could fuck. We stayed up all night fucking each other, me and abbey both enjoyed Elizabeth's nice little pussy, as it was so tight and warm. Me and abbey were so surprised that her sister new so much about sex, as she was only 13 and hadn't really hit puberty yet. The next morning we all went to get dressed but Elizabeth stopped us and demanded we stay as we are and fuck all day.