This doesn't really count as a belief, but reading someone's Roman Coke story, it reminded me of this... You know when you order something at a restaurant and the waitress/waiter asks you if you'd like a soup or salad? Up until I was about 8 or 9 I always thought (s)he was offering a "super salad". I figured it our the day I was asked if I'd like a soup or salad and I simply sad, "yes, please".
A childhood belief about general

others believed things like this
- Croutons are called "Salad cookies"Anon
- I used to believe 'three bean salad' was an extremely small entree because it contained only three beans.— queeneve
- I hated french onion soup so my dad told me that it was banana soup and i lapped it up for years.— AussieMeg
- I thought vegetarians couldn't read Chicken Soup for the Soul. — Aretia
- I used to think Tomato soup was Lava.— Daniel Green
- I used to think soup actually made you grow up.— Marie91