I personally used to believe that if I yelled into the sink loudly enough, my message would echo and travel through the pipes, into the other bathroom's sink exit, or shower exit and that they would hear me talking to them... They never did.
A childhood belief about bathrooms

others believed things like this
- If you eat 30 minutes before swimming, you will sink.Anon
- i used to believe that a monster lived in the garbage disposal. i would never go near the sink— Whitney
- I used to believe that take a shower meant to go steal a shower from the storeAnon
- 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 if you took a shower after a day of tanning the tan would come off in the shower— Shar
- When I was about 4 or 5, I used to believe that instead of bones, we had metal pipes. — TL