My first ever real life experience of masturbation happened whilst I was about thirteen and at high school. Another guy in my year and I had gone to the boy's room to pee. We were stood there at the urinal when I noticed his dick was hard. He asked me if I had ever cum. I said no but I knew what he meant as I had seen it in porno tapes.
He started to rub his hard dick and soon told me he was cumming. It wasn't white and didn't spurt out as as I had expected. It was more a sort of clear fluid which just leaked out of the end of his dick. Maybe this was because of his age. My dick had got hard at the sight of this by now, and he offered to make me cum too. Just then an older kid came into the room and obviously noticed our hard-ons and said he knew what we had been up to. It was then I realised that there was frosted glass in the room and that although distorted, we could most likely have been seen from outside. We left immediately and heard no more of it but I often wondered if we had been seen by anyone.