When my sister was 3 I told her that whenever she flushed the toilet, the sound that it made was from a giant water monster that would suck everything down the bowl, and if she was too close it would suck her down too.
The revenge for this of course was that for the next 8 years she didn't flush the toilet. She's now 16 and still needs to open the door run to the tank press the button and sprint out of the room.
A childhood belief about fear of

others believed things like this
- I used to believe that the toilet would suck me down if I flushed it.— :-)
- i use to believe that if i flushed the toilet when i was still on it would suck me down to who knows whereAnon
- I used to think if I left the toilet seat open my cat would get flushed down the toilet.— G
- I used to believe that if I flushed the toilet before I showered, I would take a shower in dirty toilet water.— Chris D
- I used to think the suction of an aeroplane toilet was large enough to suck your kidneys and spleen out.— Big Chrissy S_ _ _ _ _
- I used to think that the sound after the toilet was flushed was ladies singingAnon