I used to believe that sexual terms were bad words. I remember my friends and I would go into the girls' bathroom and whisper stuff like, "Vagina! Sperm! Periods!".
Imagine how shocked we were when the lady teachers taught us girls about periods and whatnot in fourth grade.
A childhood belief about swearing

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 thought that the difference between girls and boys was that girls have teeth.
Anon - I used to believe all babies came out as girls and later on in life some of those girls turned into boys — Tom
- 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