I used to think that "ass" meant "penis" for some reason. My best friend in 3rd grade told me that she used to have really long hair--"down to [her] ass". I was really confused and said, "You don't have an ass." She looked at me really strangely.
A childhood belief about general

others believed things like this
- I used to think that bleaching your hair meant washing your hair with toilet bleach.Anon
- When my friend told me her cat was moulting I thought she said melting. I was confused for a while.Anon
- I used to believe that "sue" meant murder, so in movies when someone is getting sued I got really confused— I don't know
- I used to think I could have my hair cut long ...Anon
- I used to think that "tease your hair" meant make fun of itAnon
- I used to believe moustaches were just really long nose hair — RaoulDuke