Ever read/seen Stephen King's 'It'? If you haven't, it's about a evil clown creature thing that kills kids and comes up through sinks, showers, toilets etc. I was deathly afraid of the washroom for about a week after seeing the movie.
A childhood belief about bathrooms

others believed things like this
- A billboard sign read: Moonshine kills.
I thought being caught outside by the moon would kill me. Humph.Anon - I used to think that gummy bears were evil and wanted to take over the world. I'm afraid of them to this day.Anon
- I believed the urinals in port-o-potties were sinks.Anon
- I used to think an evil spirit type thing called Wango lived in my dog. I was terrified of that dog.— Franklin
- I was convinced that hot air sinks. Why else are mountain tops cold, and Death Vally is so hot?— Not-my-wife
- I thought if I left the door open too long, a dog would come from the cupboard in the washroom and eat me
Anon