I heard that it was a good idea to take baths during your period, but the idea terrified me because I thought you'd end up bathing in your own blood. I was blissfully unaware of the term "water pressure".
Also, when I was about seven, seen a sign in the Ladies saying "please don't flush sanitary towels down the toilet". I knew what sanitary meant (clean) and I assumed that this meant you were allowed to flush DIRTY towels - as in bath towels. Sensible idea - no point wasting clean towels. I didn't understand properly until I was nine or ten.
Not to mention I thought you tied tampons to your underwear. All the school textbook had was a picture of a loose tampon and the words "You can do any exercise wearing a tampon, it cannot slip." Thank you, middle school.
A childhood belief about periods

others believed things like this
- I was horrified when my first period arrived. It wasn't blue, like in the commercials for sanitary towels.— Jane
- I used to believe that towels were sleeping ghosts, and at night they would come out and get you— bajd
- i used to think that you pull the string on a tampon and it would roll out to make a sanitary towelAnon
- I used to think being engaged meant being in jail. I have no idea how I came to that conclusion.— CNB
- I used to think that if you sneezed while wearing a tampon it would shoot out like a rocket. — Crazy Kid
- i used to believe that the "coin wash" was to clean my dirty pennies.— rmutt