I have a younger brother. He is kinda inquisitive and I've caught him trying to look up my skirt a few times. I guess its kinda gross, but in a way, its kinda powerful that I have something he wants to see. Sometimes I would tease him by sitting with my legs apart a little so he could see my panties. I guess he used to jack off a lot because he would go to the bathroom for ages.
One night, I had been out with my boyfried, we had made out a lot and I was horny as all hell when I got home. I decided to make myself cum before going in the house (we have a huge garden, and I can be kinda loud) I walked into the pool enclosure and just stuck my hand up my skirt and into my panties. I was just kinda getting into it when I heard a noise. My brother had snuck out for a midnight swim and caught me. I was like so fucking mad at him. Especially when I saw his boner through his shorts. I called him a disgusting fucking perv and he called me a slut. Next thing I knew we were fighting, well kind wrestling really. It was all arms and legs and ended up when I slipped and fell onto my back with him on top of me. Somehow, the dirty name calling and the fact that we were both obviously really horny changed the moment. I felt myself desperately wanting him and I reached down for his cock. It was already out of his shorts and I pressed it against my panties. We dry humped each other and I felt myself cumming. I also felt that his cock had slipped almost under my panties. He wasn't inside me or anything, but his cock grazed against my clit and it sent me over the edge. He cummed too and I felt him pump his load all over my lower tummy.
Then it hit me how sick it was that he was my own brother and all. Somehow though, that only made it better and I reached for him again. This time, I jacked him off nice and slow and made him blow his load which was much smaller all over my t shirt. Then I took his hand and made him finger me to orgasm. I guess I must have been really horny because I peed a little into his hand when I cummed. He said he liked that a lot.
Since then we have fooled about a bit, only when one of us is really horny though. We have even experimented with me peeing on him and one time, he asked to see me pee in my panties. It felt kinda gross, but it was also a turn on too.