It is so embarassing, but when I was a child, I did not understand how it was possible to make a baby with a penis since I had seen it was rather soft. You knowI I had seen small boys on the beach with no clothes on and so on. So I believed penis had a bone (!!!) inside of it, who made it hard and able to produce babies! That "bone" grew out in the teens I believed, and that was why you had to be an adult to have a baby!
A childhood belief about rude bits

others believed things like this
- i used to belive when i got an erection that if i bent my penis it would break like a bone— beep41
- i used to believe that a sign in a cafe bone-fide meal meant meat with a bone in it— roy
- I believed that women who wanted babies ate a seed, which then grew into their baby. — World's Worst Scientist
- I believed (thanks to my mum) that babies grew on "baby trees" and simply 'fell off' when they were ripe!!!— Stace
- I used to believe that gay sex involved a man sticking his penis inside another man's penis.Anon
- When I was 5 I thought that baby boys came from men and baby girls came from women...— Gaz