I used to believe that if you were a girl and you touched yourself, ahem "down there", you wouldn't end up getting your period or it would get delayed for a really long time.
I thought this when I was around 9 or 10. When I was 12, I dissapointedly found out how wrong I was.
A childhood belief about periods

others believed things like this
- My parents told me I was found under a gooseberry bush which I thought odd for a long long time.— Kate
- I used to believe that if you left crumbs out for a long period of time, they would turn into ants.— Bylaberrie
- When I was a kid, I found out about a womans period and I thought that she would bleed through her breasts.— Michael
- I thought that your period came out all at once and you had to wear a pad around the time it would come.— Sarah
- I used to think that oral sex was talking about sex. I was wrong when I found out the truth.Anon
- I used to believe that you could catch AIDS from just looking at a nud girl. Good thing I was WRONG— Mbm4615