My nephew was about 8 and thought he could fly. He climbed up the babysitter's tree, and jumped. Of course he didn't fly, but he did break his arm.
Evidently that wasn't enough, as soon as he got his cast off, he climbed back up the tree and did it again, breaking the other arm.
A childhood belief about special powers

others believed things like this
- When a soldiers went AWOL in the movies, I thought they physically climbed over "A Wall".— D Rumsfeld
- When I was five, I believed God was big as a tree, a tree being the biggest thing I could convieve of.
— Chris - I used to believe that the Doller Tree store was an actual tree.Anon
- I thought break dancing involved actually breaking stuff!— Sydle
- I used to think that partridge in a pear tree was "cartridge" in a pear tree(christmas song)— Erica
- I used to think that the tree branches moving was making the wind, not the wind making the tree branches move.— Jenny