When I was little, my cousin told me that both men and women got periods and that men gave women their periods. In response I suggested the vice versa, "and women give men men their periods?" My cousin responded by correcting me and telling me that only men gave women their periods. I didn't really wonder where men got theirs from. I seem to remember demonstrations with Ken and Barbie dolls.
A childhood belief about periods

others believed things like this
- i used to believe that women wore bras because their periods happened in their boobies.Anon
- a male friend of mine used to think that only women who had been pregnant had periods— oiman
- I also used to think that Mommies didn't have periods. I thought it went away once you had a baby.— T
- i used to think that women gave birth to their husbands and marry them...— Pat
- When I was younger, I thought that Labour Day was when all sorts of women gave birth.— Greg
- I used to believe that women gave birth to girls and Men gave birth to boys— Rob