I used to believe that if a girl didn't want to get pregnant that all she had to do was have sex with two different boys, one right after the other. The resulting sperms would fight and kill each other off before impregnation could occur. Such "birth control" ignorance of children/teens is utterly amazing and there should be sex ed, with a section on "false ideas about how to avoid pregnancy."
A childhood belief about getting pregnant

others believed things like this
- I used to believe that birth control was for deciding to have either a boy or girl babies. Anon
- I used to think birth control was where you could choose the sex of your child.Anon
- i used to think that birth control pills should be inserted vaginally. Anon
- I used to believe that mommies gave birth to girls and daddies gave birth to boys. — Jackie
- I used to believe that boys, gave birth to boys and girls gave birth to girls. How i'm so wrong now.— Sarah
- I used to believe that women gave birth to girls and Men gave birth to boys— Rob