I used to not know that it was possible to breathe out of your nose until I was around 5, and I always thought my brother was just holding his breath for a really long time when he had his mouth closed.
A childhood belief about general

others believed things like this
- I still hold my breath when I pass by cemetaries because it is impolite to breathe when other people can't.— Crystal
- You couldn't have your belly button covered for too long or it would be harder for you to breathe.— Jess
- I used to believe that the "shark mouth" nose art painted on military planes was to scare enemy pilots away.Anon
- I used to believe moustaches were just really long nose hair — RaoulDuke
- I used to believe that mustaches were grown from really long nose hairs.Anon
- When I was younger, I used to think that moustaches were just very long nose hairs.— Mike