I used to believe that urine was green. It wasn't until I was about ten years old that I realized that this was because our toilet bowl was blue.
A childhood belief about weeing and pooing

others believed things like this
- I used to believe that monsters lived in my toilet and they ate my poop and urine when i flushed the toilet.Anon
- Eifel 65 - Blue
I'm Blue (if I was green I would die...)
[I'm blue, da ba dee, da ba di.]— Matt - I used to believe the sky was green and everybody was colorblind since they said it was blue— IM COW
- I used to believe that toilet seats were for kids only and that adults sat directly on the bowl. — Evan Klyne
- i used to believe that people with blue or green eyes saw that certain color— mellactica
- that the green traffic light turned blue when it was off— Kriket Evens