When my sister and I were little, my mum used to tell us she could see through walls.
Every time we tried to steal biscuits from the biscuit tin, she would shout from another room "I can see through walls, you know!"
We boasted to all of our friends that our mum had X-ray vision and really believed it, for years!
It was only later that it dawned on us she could just hear the sound of the lid being lifted...
A childhood belief about magic tricks

others believed things like this
- I believed God lived in a specific crack in one of the walls of my church — Blake
- I once believed that the walls and ceilings were completely jam packed with plumbing and wiring.— David
- I sused to believe dinosaurs lived in my walls.— Joshua
- When I was little I thought that a "wallflower" was a kind of flower that grew on walls.— A. Nonny-Muss
- That blue cheese was made by scraping mould off bathroom walls. My mother actually told me that.— sandee
- i would never eat biscuits with currants in because someone told me they were flies.— ahab