When I was little I used to have a big fear of demons. So I started to believe that if you flushed the toilet while still sitting on it you would be sucked into hell and demons would spread poop all over you. I had a similar belief about the bath tub drains.
A childhood belief about fear of

others believed things like this
- As a kid I thought dogs stupid but funny and that cats were evil demons. — Gemini
- I used to believe that monsters lived in my toilet and they ate my poop and urine when i flushed the toilet.Anon
- I used to believe that everything you flushed down the toilet ended up in "Hell".— Abi
- I used to belive that when I would poop I was feeding all the fishies that got flushed downthe toilet!— Fish Feeder
- I used to belief that mermaids lived in underground drains. Anon
- i thought that new disney peter pan song said "spread your legs" but its really "spread your wings"— shasta