When I was young, my sister who is 6 years older would have to babysit us all summer long. To keep us in line she used a metal yardstick (which she called "the beater".) Although I don't think she ever actually whacked us with it, for years I thought a wodden yardstick was called a yardstick, and the metal ones were called beaters.
A childhood belief about around the house

others believed things like this
- I used to believe that Metal music was when a bunch of people would bang metal together to make noise. Ha ha.— Kassandra
- When I was little i thought lb for pounds was pronounced lubs, and i called them that for 2 years. Anon
- I used to think if you caught a cold during summer, it was called a "hot".— Brandon Campbell
- I believed that the breed of dog called Boxer was called that because they could stand up and box.Anon
- My mom used to think "preschool" was called "pretty school" until a few years later.— Molly
- I used to believe that people from Holland were called "Hollish", like people from Poland are called "Polish"— Sally