A girl I knew in the fifth grade told me something that I believed for a long time. Think about it. Once being told this, one would have few occaasions to hear it refuted. What she told me was that girls have only one kind of feeling telling them when they need to "go to the bathroom". So therefore, she told me, girls never know in advance whether they have to do "number one" or "number two", or both. They have to look in the potty to see what came out, in order to know what they did, so the story went.
A childhood belief about weeing and pooing

others believed things like this
- In first grade a boy told me that he could see girls naked with his microscope lens. I beleived it for years.— Jeanette
- when i was little i believed that your social security number was the number you were born on the earth — christine
- I thought everyone only had a set number of breaths before they died.
I breathed slowly for a long time.Anon - When I was a little girl, I believed that all cats were girls and all dogs were boys. :)— Mary Ellen
- When I was a kid I believed that the number 11 was pronounced "onety-one"— Alicia
- I thought that the difference between girls and boys was that girls have teeth.
Anon