I used to believe that Koosh balls had batteries in them, and when you touched them, that's why they shook for so long.
A childhood belief about toys

others believed things like this
- i always thought it was Grape Balls of Fire instead of Great Balls of Fire— Courtney
- I used to think Elvis' "I'm All Shook Up" was "A Mushy Cup". How sad of me to confuse the lyrics of a king...— Sad, Sad, Girl
- my nephew used to believe that when people died, they just needed new batteries.— p-daddy
- I used to believe that I could make a laser by putting more batteries in a flash light.— Tyler
- I used to think that putting batteries in your ears could electrocute your brain. Hahahaha.Anon
- I used to suck on the ends of batteries intent on gaining super electric powers. Anon