When I was in elementary (about 2-3rd grade), my classmate and I were talking about penises and one of them said that once you get really old your penis will shrink until it disappears. So after hearing that story, most of us believed that our Granpa's just have long sagging balls.
A childhood belief about rude bits

others believed things like this
- If you pee in a pool, the pee disappearsAnon
- I used to think that girls had "balls" and not boys, and the "balls" were slang for breastsAnon
- I use to really belive if I pulled my granpa's finger I would hear a whistle..
ya right— Numnuts© - When I was about six, I believed that boys had buttons on their penises--one for pee and the other for poop.Anon
- when i was younger i believed that when two guys had sex they would sword fight with their penisesAnon
- when I was little, about 4th grade, I thought that when a guy had an erection his penis turned colors...lmao— peanut