Up until I was in high school I had an irrational fear that a monkey's paw lived in the plumbing in our bathroom. I regularly had nightmares about it attacking me.
A childhood belief about bathrooms

others believed things like this
- I used to believe that my school teachers lived inside the school and my school bus driver lived on the bus. Anon
- I used to believe you got high tides when the sea was full (I lived on the Thames, then) — rosy
- I used to believe that you got married right after you finished high school or college. Anon
- I thought that wars had to last four years... just like high school and college.— A. Falk
- When I was young, I honestly believed that I would die before I reached high school. Anon
- Until I was in High School, I really thought that the "underground railroad" was under the ground.— S