I used to think that a prostitute was a woman who had sex with other women. This belief persisted until I was well into junior high (14 years old). Little did I know I was to realize not too much later in life that I too was a prostitute -- err, lesbian. ;)
A childhood belief about sex

others believed things like this
- I used to believe that a prostitute was like a prosecutor.— Not As Innocent Anymore
- Until I was about 11 or 12 I thought that "prostitute" referred to a female criminal.Anon
- i used to think that being a prostitute was a religion. (sort of like protestant i guess?)Anon
- I thought that sexist was another name for prostitute (like a scientist does science so a sexist does sex!)— Netrom
- Until junior high school, I thought Monty Python was a wrestler.— Jamie
- I used to belief that women had babies by pressing their belly buttons!— amy