When I was 13, I just had to show my 12 year old cousin what I had discovered a few months earlier, so I pulled down my pants and let him watch me jerk off. That day, I couldn't convince hm to try but the next day he did let me try doing it on him.

We were standing facing each other (it was summertime) and we had our shorts and underpants pulled down to our ankles. I started stroking his erect penis and he told me it felt nice. Then, without any warning or saying anything, he started shooting cum! I felt it hit my leg! It was the first time he ever had an orgasm or saw that he had semen. When we were done and I pulled my pants up, I discovered that a big glob of his cum also landed in my underpants. So for the rest of the day I was wearing damp underpants from his cum. (It landed in a spot where it was right under my balls.)

We continued to masturbate together until just before I turned 16. Then girls pretty much took over.