When I was little, my mom finally told me about what was going on 'down there' when I went to the bathroom. For the longest time, I thought that the urethra (or however you spell it :/ ) was called your Aretha, as in Aretha Franklin, the singer. I still can't keep a straight face whenever I hear that name!
Also, this is not really a belief, but, when I was around 3 years old, whenever I had to go to the bathroom, wherever I was I would pull my pants and underwear, or drawers if you're British, and THEN run to the bathroom. I have no clue whatsoever why I did this. We even have pictures which I'm sure my mom will make use of when I bring my first serious boyfriend home...
A childhood belief about weeing and pooing

others believed things like this
- I used to think that Aretha Franklin's name was Urethra Franklin. Anon
- I always thought that "Staying Alive" by the Bee Gees was sung by Aretha Franklin.Anon
- someone told me that if u go to the bathroom on the toielt you would get sucked inn..— terrified child
- Grandmother told me if I whistled in the bathroom the devil would come get me because I was whistling for him.— Peanut @ Lake Tawakoni Tx
- When I was little, I thought it was harmful to eat while you were going to the bathroom. Anon
- That blue cheese was made by scraping mould off bathroom walls. My mother actually told me that.— sandee