I once refused to believe in Thursday. I'd heard there were seven days in a week, but could only name six.
A childhood belief about general

others believed things like this
- I thought that "tomorrow" was one of the days of the week— Frank
- I always thought that after 1999 it would be 1990 again, but with different months and days of the week
— optional - i used to believe ketchup was blood and refused to eat it with anything Anon
- My older sister used to tell me that ants were bees. My mom was very confused when I refused to go outside.— Paulette
- My mother used to call my behind "a paw paw" and for many years I refused to eat paw paws (papayas)— Garth
- I always refused to eat coffeecake because I thought it was made with coffee grounds. Anon