When I was 17 I caught my 15 year old brother masturbating in the bathroom. He was sitting on the toilette with his pants and underwear down by his ankles, his hand around his hard dick an piece of folded toilette paper on his chest. I had seen his dick before but never with an erection. He was so scared I would tell my Mom, I shout the door and forced him to do it in front of me. He was obviously embarrassed about me watching him jerking off, but realized it was the only way to keep me quiet. Sat on the edge of the bathtub, watched him stroking his dick till he ejaculated all over his chest and then walked out quietly. I knew I had done an evil act but it was so sexy I could help taking advantage. He look embarrassed and humiliated for days, scared shitless I would tell, but that was just what turn me on. I had him with his back against the wall and knew I could force him do anything I wanted. I kept my promise but told my girlfriends about what happed. They all thought it was the sexiest thing they ever heard and flooded me with questions and details about it. I had to tell them he had a pretty good size dick for his age. We talked about for days and somehow the idea of forcing him to do it in front of them came up. When I told my brother about it he said "no way" but later changed his mind. Told him it was better to humiliated himself in front of my two girlfriends, rather than having girls in school knowing about it. We did it in a laundry room behind one of my girlfriend house before her parent came home from work. Told him to get undressed and one of my girlfriends got him off with a blow job. He lost his virginity to my girlfriend Elsie and came instantly while my other girlfriend stood watching. He was embarrassed and quiet, but shore he enjoyed not having to do it by himself. I think what kept it a secret, was because we were all embarrassed about the whole thing and scared about everyone else finding out.