Seeding the grass in the park
I go walking nearly daily on a concrete path that runs through the park. It's a couple of miles long. Sometimes I'll walk the dog, sometimes I'll go by myself, and sometimes I'll walk with a friend.
Two months ago I was walking with a friend. We're fit but in our mid 30's, attractive married mom types. It was a weekday in the mid-morning, so there were few people around. A guy on a bike came up behind us and said "I'm on your left" and we moved over, as the path is narrow. We didn't think much of it. We kept walking and talking when we came around a bend a few minutes later and the guy who passed us earlier had pulled over, was sitting on the edge of a bench, cycling shorts down, and had his cock out. He was maybe early 20's.
I looked at my friend like "wtf" and we just stopped in our tracks. The guy kept stroking his dick, and tbh he was really attractive and his cock was beautiful. It was a good 7" and thick, circumcised. He saw us, smiled, looked down at his cock, and just kept working it like we weren't there.
I asked my friend if we should turn around, and she whispered "No, let's see him finish." It took couple of minutes, but huge jets of cum started flowing, and it was pretty hot. I don't think I'd ever seen a guy cum that much. He was shooting streams for 15 seconds or so. The look on his face was pure ecstasy, amazingly hot, even though what he was doing was totally creepy and inappropriate.
We kept walking and didn't see him again, but by the time we got back to my place we both admitted that he was hot as hell and the show had gotten us a little wet. We've been out on walks a dozen times since then, but we've never seen him again.