I used to think that girls became anorexic whilst having their periods because they were too nauseated to eat anything, since loss of periods is one of the symptoms.
A childhood belief about periods

others believed things like this
- When my mom was a child, she thought that while girls had periods, boys had hemorrhoids!Anon
- I used to think that guys had periods, too. — Laurie
- I also used to think that Mommies didn't have periods. I thought it went away once you had a baby.— T
- i thought the phrase "getting a boner" referred to men getting their periods. — astrid
- i used to believe that women wore bras because their periods happened in their boobies.Anon
- i used to believe when iwas young that during periods, one bleeds through thier breastsAnon