When I was little (and this only happened in my own house) if I went into the bathroom and the shower curtain was closed, I would yank it back to make sure there wasn't anyone there, waiting to kill me while I was peeing. Sad thing is, I'm 16 and I still do it.
A childhood belief about bathrooms

others believed things like this
- I used to think when I peed in the shower as a kid, the water coming back through the showerhead was my pee.— gregg
- I used to believe that take a shower meant to go steal a shower from the storeAnon
- I used to believe Serial killers would break into your house and stab/'kill' your cereal.— mary
- I used to think that toilets led to the shower head. That's why I never took a shower :D— scared
- I used to believe that when I went to sleep, my Barbie dolls would make out and plot to kill me.— ClaireRat
- I used to believe that if you took a shower after a day of tanning the tan would come off in the shower— Shar