I used to believe that snot was actually waste from your brain ("brain-poop") and that when you had a cold and your sinuses got stuffed up, it was your brain suffering constipation.
A childhood belief about general

others believed things like this
- When I was little, I used to believe that snot was brain juice.Anon
- When I first saw a picture of the human anatomy, I thought the brain was really snot.Anon
- I used to believe that people who wear glasses did had a second brain!— Onessa
- i used to believe that if you picked
your nose your brain would cave in...— mr bogtrotter - I used to believe that if I threw up too hard my brain would explode.— Tammy
- When I was little I believed that boogers were parts of my brain that got used up.Anon