When I was an older teen, my parents took us to an out of state amusement and water park. It was blazing hot so we spent most of the time at the water park during the day. Washrooms were spread out around the park in various places, mostly off the main paths.

I had the urge and found the closest one. I used the washroom and found afterwards that you had to exit through the showers. As I entered the large shower room, a lone guy , about 25 or so stood with his back turned to me. As the water cascaded down his chest and shoulders I passed by. Just as I got up to his side, he turned so I could see his cock head sticking out of the top of his trunks. It was large and purple. I could tell he had a good size and very hard cock trapped in there.

He turned slightly again and I realized that he was using the force of the shower water to massage the head of his cock. He arched his back  and pushed the head directly under the stream. I stuttered in my steps and as I was about six feet past him, I turned to get another look. He didn't even acknowledge me there but bucked his hips and bent his knees in enjoyment. I walked another four feet or so and turned once again only to see his cock erupt with ribbons of cum that hit the shower floor and ran to the drain. He stroked his cock a few times  to clean off, rinsed his hand and smiled at me.

Shocked, I went back to the water park, but that's all I could think about the entire evening.