I used to believe that when people said that they were in their "birthday suit" they were talking about a clown outfit.
A childhood belief about appearance

others believed things like this
- Up until I was almost 11, I thought that a birthday suit was a special outfit you wore only on your birthdayAnon
- I used to think that a birthday suit was a special outfit you wear on your birthday— Bri
- Oldies Song Peggy Sue. I used to think that he was talking about how much he loves his "Baggy Suit".— Randy
- I used to think that Batman was Blackman. He wore a black superhero outfit, so it made sense to me.Anon
- I thought that people with the same birthday were always the same age.Anon
- I used to believe that people only grew, physically and in age, on their birthday. — Aretia