I used to believe that cows slept underground.
I think my parents must've told me they slept "on the ground," but I didn't heat them correctly...thus the underground belief.
A childhood belief about general

others believed things like this
- I used to believe that the cows owned by my grandfather slept lying on the ground like a human at night.— Eric
- Until I was in High School, I really thought that the "underground railroad" was under the ground.— S
- I used to belief that mermaids lived in underground drains. Anon
- that hills were giants buried underground...— tracy g
- I thought the underground railroad was actually a subway.— Greg
- That there was an underground tunnel linking New York to San Francisco.— Christophe Chang