ok this is a good one...
I was like, 7 (I started developing sexuality early, I got my first boners when I was 3 or so (over other 3 year olds), the concept of masturbation was not unheard of with me when I was 5 (while thinking about other 5 year olds at that point) but I never came.
My mom told me if part of you itches a lot, you ought to vigorously rub lotion on it.
Well, I'd been rolling around on the grass a bit, and I guess my penis itched consequently (can you see where this is going?) So I'm rubbing lotion on my cock... I get hard... It still itches so I rub harder... All of a sudden there's more "lotion" than I started with and I feel really effing weird.
Was terrified of my penis for 5 more years. When I was 12 I rediscovered my penis. And the internet. The rest is history.
Slade