I used to believe that the "invisible" or "clear" paint used in cartoons exsisted. (you know the paint the charaters would use to be invisible and then foil the plan on the vilian or hide)
A childhood belief about cartoons

others believed things like this
- Yesterday I realised that invisible ink doesn`t make me invisible.— Jonathan Eleven years old
- I used to believe that if you mixed red, blue, green, and yellow paint you'd get plaid!— Judith Ann
- My sister once asked her mother why she didn't paint her black....Anon
- When I was little, I thought that clouds were made by someone spraying white spray paint onto air.— Hadla
- I thought that the jetstream from planes was white paint. Which was constantly poured out from the plane.— Tore
- I used to believe that when you closed you eyes you were invisible and no-one could see you!— Andrew