I grew up right by the ocean, but refused to learn to swim because the water was green. My logic was as follows:
Water is blue.
Wee is yellow.
Blue + yellow = green.
I was convinced the ocean was green from all the people weeing in it!
A childhood belief about water

others believed things like this
- I used to believe that if you mixed red, blue, green, and yellow paint you'd get plaid!— Judith Ann
- i used to believe that people with blue or green eyes saw that certain color— mellactica
- 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 that red yellow and green meant "ready, set, Go!" on traffic lights..— cabagona
- I used to believe the sky was green and everybody was colorblind since they said it was blue— IM COW
- that the green traffic light turned blue when it was off— Kriket Evens