My sister and I used to pee on each other when we were kids. We loved it. Sometimes she would leave her knickers on and sit on my lap to piss. after she turned 13 I spied on her losing her virginity and she saw me watching. A week later we got home from school to an empty house and she asked if I enjoyed watching her fuck. I told her yes, and that I miss pissing on each other as well. She took me into the garage made me sit down and lifted her skirt. She had had sex right before we caught the bus home and his cum was still in her panties. She had made him pull out but he filled her knickers. It was beautiful. Susie moved closer to me and started to piss herself. It was filling her undies and running down her legs and looked so good I grabbed her hips and started licking her. She started to moan so I slipped a finger in her tight pussy and started to wank myself. After a few minutes I laid down in the floor and Susie squatted over my cock and slowly lowered herself onto me. I came inside her twice in 5 minutes.