When my step dad farts it sometimes makes sort of a quack sound, so when I was a kid, after he would fart, he would say "whoa, did you see that duck run by?!" Then I'd actually go looking for the duck. This also made me believe that ducks could run so fast that you couldn't see them, cuz every time "a duck ran by" I couldn't see it.
A childhood belief about farting

others believed things like this
- i thought that "aromatic" duck was actually "asthmatic" duck.
poor thing...— rachael - I always thought that duck sauce (from chinese restaurants) was duck poop.
— emily - Whenever I was upstairs on a bus, I didn't believe that it would fit under the bridge so I used to duck. — Dave, Lancashire
- I used to belive that if I didn't duck when going under bridges they would hit me.Anon
- My mother's name was Anna. She was called "Annemor"(Duck mama). I was convinced I was a duckling.— Christine Norway
- I thought ducks couldn't fly - thats why they swam.— G