I used to beleive a condom was to prevent you from peeing inside the woman, which would cause her to inflate.
A childhood belief about condoms

others believed things like this
- When I was first told about intercourse, I didn't believe it. How could peeing inside a girl make a baby?— Art
- When i was young I used to believe if I ate ham fat I was going to inflate like a balloon— a guy
- up until puberty I thought that my nipple would inflate like a balloon to form a breast— EiEi
- I used to beleive that little drawf men were inside each traffic light, making them change colors. — alisha
- I used to believe my dentist could give me a shot to straighten my teeth and prevent cavities.— sircigar
- i used to believe that when you had diahria you were peeing out of your butt.— roger rabbit