It was summer, and I guess about 1958. We were 12 yo, and had six weeks off school. John's dad owned the village pub, an old rambling place at least 300 yo. I guess we were pretty naive when it came to sex, and considered "who could pee the highest against the wall" as daring. We would hold these competions in the pub toilet, which, in those days was a separate brick building in the yard at the back of the pub. Adjoining the toilet was another flat roofed building which John's dad used to store his crates of bottled beer. It was on this roof that we would hang out together, access was by some strategically placed beer crates.
I remember the day well, when John produced a "Health and Efficiency" magazine, someone had stuffed it behind the cistern in the lav. H&E was the nearest you could get to porn in those days. By today's standards it was pretty tame, but to a 12yo then it was dynamite. By the time we got to page 5 both John and I had hard ons, our small **** cocks straining within our trousers, watching John constantly adjusting his restrained cock I suggested we got them out. And so it continued for the next couple of weeks, the pair of us sitting side by side, stroking our cocks slowly leafing through H&E.
Although we had heard about masturbation, and felt incredibly near to cumming during our "stroking" sessions, it had never happened, probably due to our age and anxiety in general, however this all changed just before the holidays ended. We were fishing down by the local river, talking as usual about the merits of particular women in our H&E (we knew them all by heart by now) when suddenly out of nowhere a man appeared. He was about 30 a little overweight and dressed for hiking, complete with shorts and boots. He never spoke, just smiled, unbuttoned his fly and took his penis out. Compared to our cocks it appeared huge and was not even fully hard. Still not speaking he stroked his penis up and down, just as we did. The purple head slid in and out of his ample forskin getting bigger with every stroke. We watched fascinated, and then suddenly slowing, he pulled his foreskin as far back as it would go, the now huge purple head pulsed as the first of five or six jets of cum arched into the grass beside us. He wiped any remaining cum onto his finger, licked it clean, slipped his penis back into his trousers, smiled at us and walked off buttoning his flies up.
Back on our roof that evening, hunched over H&E, we talked about how the man had made himself cum, needless to say within ten minutes we were spraying cum all over our rooftop hideaway.