When I was younger the street lights used to shine through the trees in our front yard. I had a thick-ish curtain covering my (floor to ceiling) glass doors to my balcony and the image that projected onto the curtains from the lights and the trees looked like a man holding an axe about to kill someone.
I was so traumatised from sleeping in that room just from trees and lights.
Overimagination from that led me to think for years that there was someone hiding under my bed and in my closet ready to jump out and get me.
A childhood belief about in my closet

others believed things like this
- I used to believe wind came from trees. And when it was really windy, the trees were really mad.— Tiffany
- I believed that traffic lights had police officers inside them, turning the lights on and off...— CrowHeart
- when i was about 5-8 i used to believe that oompa loompas lived in traffic lights and controlled the lights!!— ~wierd ~
- I used to believe that trees made the wind, but its the wind that blew the trees!— victoria
- I used to believe that the wind was caused by trees so you could stop the wind by getting rid of trees.— Nira
- i used to believe that if i looked at trees, the wind would start blowing. Anon