I used to think if you weren't quick enough getting off the airplane toilet seat, you would be flushed down the toilet and out into the air.
Admittedly my Dad had a part to play in that - telling me the toilet waste flies out into the air like it used to do (true) on train toilets - straight on to the track.
Eww huh?
A childhood belief about general

others believed things like this
- 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 when you flushed an aeroplane toilet the waste would just drop out of the plane.Anon
- 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 if I flushed the toilet before I showered, I would take a shower in dirty toilet water.— Chris D
- I used to think you could get pregnant by sitting on a toilet seat.— Lisa
- I used to think that boy's lifted the toilet seat to pee because their asses were too big.— sydo