I was around 15 and spent the night at a friends house. His parents drank ALOT and once they passed out they were out. Well his sister the first time I spent the night she snuck into his room and he was practically asleep. Back then I slept in underwear. She eased into bed with me ,she was lil 13 two years younger than me. She slipped into bed and said I want to know what one feels like is it ok if I play with it. (she already had large breast) I told her ok ill tell you what take off your top and ill pull off my underwear. She said really,you mean you will pull them completely off. I said yes. She took off her shirt I slide off my underwear. We kissed and she felt me up I sucked her tits and played with them and was do excited I was pulling her panties down. After grinding her in her thin panties. Well I got her panties to about her knees and her brother turned on the light and said I thought you were in here. And told her to get out. I told him hey leave her alone let us have a little fun. So he walked over and snatched the covers off us. There I am pointing straight up and her there nothing but panties around her knees. He said holy crap you guys are really about to do it. He walked back and cut the light off and walked out. She jumped up and started getting dressed. I said wait he is giving us time to do this. She said no he is going to get my mom or dad here put your underwear on hurry. She jumped up and ran to her room. I laid back down underwear on still rock hard. And I pulled the covers back up. His mom and him came back in the room and his mom looked and said where's your sister he said she was right here he pulled the cover back and there I am in my underwear tock hard still his mom looked and said well she isn't here now. She looked and she was in her bed. She told him shut up lay down and dont bother me anymore. Do he did. Years later I was about 21 she and I ran into each other at a party and she said hey I owe you something dont I. We rode off to get beer and she stripped naked and said ok come get what I owe you. We had sex tight on the side of a country road in my truck. It was plenty of fun that night. She came back about 8 times but then she got a boyfriend and years later than that we hooked up once again but at my house. She was a fun girl.