My sister had just got the grasp about the difference between girls and boys and that some parts of the body change when you get older - girls grow breasts and men get larger penises.
We stood in line at the post office when a very tall man came in - and she said loud and clear: "Do you think that man has an elephant penis?"
A childhood belief about rude bits

others believed things like this
- I thought that the difference between girls and boys was that girls have teeth.
Anon - I used to believe both boys and girls had penises so i thought sex was when they tied them together.Anon
- When I was little I thought girls had "man parts" as well, but it just took longer for them to grow.— person
- I used to believe that condoms were weared by girls and boys
both. And they both have penisAnon - I used to think that girls had "balls" and not boys, and the "balls" were slang for breastsAnon
- I used to believe all babies came out as girls and later on in life some of those girls turned into boys — Tom