My sister and I used to believe that pigs didn't have tails. We tried to remove them from our piggie banks. Later, when we were old enough to work on the farm, we helped cut the tails off young piglets. So then we knew that pigs do indeed come with tails.
A childhood belief about general

others believed things like this
- That hot dogs were made from rat tails.Anon
- When i was little, i thought dogs poop from their tails.Anon
- When I was little, I used to believe that wind was caused by whales flapping their tails way out in the ocean.— Nanohawk
- I used to believe that waves were made by whales who lined up in a row and flapped their tails.— Passionola
- I thought a Monkey was just a baby Gorilla and when they grew up their Tails fell off!— Brainhead
- sheep were wooly pigs— CJ