Our French teacher always reminded us that "poisson" (meaning fish) had 2 "s"s. If we only put one "s", it was "poison". I took her literally, in that I thought if I spelled the word with one "s", the word would somehow turn poisonous. I never worked out the logistics on that.
A childhood belief about foreign languages

others believed things like this
- I used to believe the word shoes was spelled shouse. It looked right to me... — Shouse
- In first grade, I thought that if I've never heard of a word before, then it wasn't a word.— Destiny
- I used to think the word fever was just another word for giraff— Marshall m
- i used to believe if i eat fish it would turn my stomach into a fishtank and make me turn into glass.Anon
- I thought if someone is in a vegatative state they literally turn into a giant vegetable!— Samilton Duerheiser
- I used to believe that the rapper Eminem's name was spelled M&M and anyone named Juan was spelled one.Anon