When my little brother was 6 years old, I told him that those little dust particles floating around in the light of the window were actually little monster alien things that lived on the sun, called Megamimas. They transported to Earth by travelling on rays of sunlight. I told him that they bite, and the bites were extremely painful for their tiny size. My grandfather is missing a finger on one of his hands (it got shot off when he was in the Navy), and I told my brother that a Megamima bit his finger off.
He avoided windows during the daytime for a long time.
A childhood belief about monsters

others believed things like this
- My older brother once told me that Aussie shampoo was made from kangaroo pee. I avoided using it for years!— Annie
- my grandpa told me if you pick your nose too far then a snail will bite your finger off haAnon
- my brother (10) still believes that if you stick your finger to far up your nose you can touch your brainAnon
- I used to believe that a half moon was gods finger nail, and his finger was pointing downwards.— clo
- I used to believe that if you picked your nose far up enough, a snail at the top would bite your finger.— Jenny
- My mom told me that if I picked my nose, my finger would stay there someday!!— baxter