Until he was 12 and my mom explained it to him, my brother was convinced that pads were "vagina protectors" and were worn to keep any germs from getting into the vaginas. He even demonstrated how they were put on to me (very gross), by sticking the adhesive side to the crotch. I tried to tell him he was wrong, but he wouldn't listen. It was very funny when it hurt him to take it off, though.
He also believed that tampons were inserted into someone (man or woman)'s butt if they had to poop but didn't want to because they were in a public area or something. The tampon would stop the poop coming out so the person could wait until they got home to go in privacy.
A childhood belief about periods

others believed things like this
- I used to believe that maxi pads were worn backwards with the sticky side on your.....tutu.Anon
- I actually asked my mother if mixing girls' poop and boys' poop would cause an explosion.— kraine
- i used to think that your butt cheeks is where your poop was stored. Anon
- i used to think there were little mini oompa loompas inside of me that pushed the poop out of my buttAnon
- My poop was always around the same color as my skin so I assumed white people's poop was white.— jaycee
- when I was little I used to think that white people had pink poop (i am brown so my poop is brown)— helena muteka