When I was little, my sister convinced me and my brother that when you flush the toilet, the "stuff" being flushed went through an underground tunnel to the mailbox, and that the mailman picked it up and brought it somewhere.
A childhood belief about general

others believed things like this
- That there was an underground tunnel linking New York to San Francisco.— Christophe Chang
- I used to think underground trains actually descended into the tunnel, like a rollercoaster.— Natasha
- I used to think that the word mailman came from the fact that the mailman was a male. I don't really know why.— Andi
- My brother (who was 6 at the time) would never flush the toilet in fear of our new house being blown up! Anon
- I used to beleve when i was 4 that the flush on the toilet was to wake up toilet monsters.— Millie
- I used to believe that monsters lived in my toilet and they ate my poop and urine when i flushed the toilet.Anon