I used to believe that my parents had installed a camera behind the (two-way) bathroom mirror. I used to cover it up with a towel so they couldn't see me naked!
A childhood belief about mirrors

others believed things like this
- I thought if you point the video camera at the TV then both the video camera and the TV will explode.
Anon - I used to believe jaywalking meant walking around naked in public (from naked as a JAY bird...)— Izzi
- when i was young i used to believe that my image on a mirror would come to life if i broke the mirror.Anon
- My mum used to tell me that you couldn't drink water out of the tap from the bathroom as it was poisonous.Anon
- I used to believe,there was a little person inside my Dad's box Brownie camera.— Sandra R
- I used to put a camera along my fireplace on Christmas Eve in hopes to tape Santa.Anon