I went to "private" catholic school as a kid, but I had friends that went to "public" schools, so when I saw signs that said "not open to the public" or "private", I figured I was allowed in there. Unfortunately for hilarity's sake, I never tested my theory.
A childhood belief about classes

others believed things like this
- When I was a kid, I wondered why they called it "public hair" when it was so private.Anon
- I always though as a kid that "To Let" signs were public conveniences with an I missing. Really.— Col
- I thought the "To Let" signs on buildings meant they were public toilets.— Scottish Laddie
- i used to believe that public houses were just houses were the public could go and liveAnon
- When I was a child, I used to believe that armpits were private parts— Duda Gueiros
- I thought there were only four ranks in the army: private, corporal, Seargeant, and General— Alberto Richardson