When I was young, around 7, my Dad warned me that if I played with my penis it would eventually turn black and fall off. Well, he was a recently-retired nurse, and I had absolutely no reason to disbeleive him - he'd given me tons of information on the human body already. Of course this was completely and totally untrue. However, I beleived it for a long time, and didn't really discover masturbation until I was thirteen, after I managed to convince myself that it was a lie. Actually, in his mind, he wasn't lying to me - I asked my Dad about it and he said he really beleived it, as a kid and still today.
He's 70 years old. For his entire life, ALL SEVENTY YEARS OF IT, he truly and totally beleived that masturbation would cause penises to turn black and fall off. He's probably never masturbated in his life.
The thing is, though, it was probably because he was raised in a family that were very likely prudes. I guess we can't really blame him. Still funny, though!
A childhood belief about rude bits

others believed things like this
- In first grade a boy told me that he could see girls naked with his microscope lens. I beleived it for years.— Jeanette
- If you suck your thumb it would eventually go black, shrivel up and fall off.— Charlotte
- I beleived that the reason Birch trees were white was because they saw Casper the Freindly Ghost.— Anela
- i once beleived that if i did not eat any food, god would punish me— andria
- in kindergarden i beleived that to be a teenager your name had to end with teen— eric
- i beleived that once the tiolet was a big dinosaur and if i sat on it, it would eat my bum and send me to jailAnon