I watched Charlie Brown a lot when I was younger, the one where he's in a spelling bee.
There's a bit where he exclaims "I'm a failure!!!"
I thought it was perfectly normal to say that so whenever i failed a spelling test or something i would say that to my teacher.
Eventually she called my mum in thinking i had self esteem issues.
A childhood belief about cartoons

others believed things like this
- I used to beleive that a catacism(spelling?) was an extremely painful Christian version of a bris.— Mike
- When i was younger up untill i was like 8 or 9 i thought that famous people didnt poop only normal people!!!— kaitlin
- i used to think chocolate milk came from brown cows and normal milk came from white cows Anon
- My mom always used to tell me that brown eggs came from brown chickens.— Taylor
- I used to think you could have a heart attack if you failed to fall in love.Anon
- when I was little I used to think that white people had pink poop (i am brown so my poop is brown)— helena muteka