I used to believe, when I was very young, that as women had no penises, women had no private parts altogether. How did they use the toilet, you say? Easy: they peed through the anus.
This belief was revoked when I discussed the matter with my brother, who cracked up laughing saying, "Imagine how disgusting it would be trying to pee and crap at the same time!"
A childhood belief about weeing and pooing

others believed things like this
- I used to belief that women had babies by pressing their belly buttons!— amy
- when i was young i believed that gay men got married to gay women!— robster
- When I was a child, I used to believe that armpits were private parts— Duda Gueiros
- I used to belief that the Muslim women who wore their garment wore it because they were bald.Anon
- I was scared that if I peed too much, the toilet would flood— scarlett
- I used to think that women urinated out of their buttholesAnon