Man, do I ever love this site!
I was watching my step-dad's younger 17 year old brother(my step-uncle?) masturbate at our computer one nite. We were alone in the house and he thought I was upstairs in my room.
He was sitting in his boxers stroking a good 7 1/2 inch uncut cock, the same size as my step-dad's. I seen my step-dad jack off in the garage plenty of times but never mutually jacked off with him even though I jacked off my self thinking about it.
Uncle turned around and saw me. I thought I was in for it but he just said 'come on Jim, sit down here and we'll jack off each other.' He didn't have to ask me twice and we had an enjoyable evening with about 2 hours of cock play.
Uncle lived out of state and while he stayed with us for a month we masturbated each other everyday and somedays 2 times. I was 15 with a 6/12 in. cock and I'm still not over my good fortune at beating off with a great guy with a great cock.