As a young child, the basic mechanism of reproduction was explained to me, but not in detail, and I thought that testicles were what were "ejected" (whole) into the female's body, which sounded painful, and then you grew another one in its place.
A childhood belief about rude bits

others believed things like this
- When i was little, i thought that when i grew up i could only have two kids because i only had two testicles.— nick
- I used to think that prostitutes were female lawyers. It just sounded so official...— MC
- When I was young I used to think my testicles held the pee!Anon
- My cousin thought the BASIC computer command GOTO was prenounced "Got-oo" rather than "Go To"— Richard Davies
- I used to belive that if you didn't step off the escalator in time you would be sucked into the mechanism.— Houdinia
- When i was little i used to think that a birth mark was the place on the body where you came out of the mother— bipbop