I know this one is very common, but I'm gonna submit it anyway. I, like many of us, used to believe that stupid little kids were the only kind of little kids that existed. We all used to believe that at some point. I mean when you see an anonymous 5-year-old throwing a tantrum, or an anonymous 5-year-old doing bawling, or an anonymous 5-year-old whining, of course you're gonna believe that stupid little kids are the only kind that exist.
A childhood belief about getting older

others believed things like this
- I used to think that Anonymous was a really famous person— Anonymous
- Up until I was 10 or 11, I thought the word anonymous was 'annoymous'.Anon
- i used to think that Anonymous was a super famous person and Anon was his side-kick XD— AJ aka adrienne
- I used to believe that anonymous was a person, and I thought, "Gee, this person writes a LOT of poems!"— Katie Albano
- Abba - Happy New Year
"Kangaroo year,
Kangaroo year..."— Santa Puncher - When I grew up, I was going to be a mom with no kids.Anon