I used to believe that poo was kept in the buttocks and ergo fat people must do bigger poos. Despite a medical degree, I am still having problems removing these thoughts.
A childhood belief about weeing and pooing

others believed things like this
- i used to believe that people's buttocks were plump because of the poo filled in it— Diesa
- I used to think that poop was stored in your buttocks and that's why they're squishy.Anon
- Since my father had a deep cleft in his chin, I thought he was growing a tiny buttocks out of his face.— Rick
- I thought that big people are necessarily smarter because there brains would be bigger— Quatsch
- I used to think that blood flowed down one leg and up the other.
And I'm applying to medical school....— Nat - I used to believe that "critical acclaim" meant that they liked it, BUT had some major problems with it, too.— Beth