It's probably unfair to snitch on someone who's not here to defend himself, but someone I knew used to think Nirvana's "I'm a Negative Creep" was "I'm an egg in a tree". Oh for shame.
A childhood belief about misheard lyrics

others believed things like this
- I thought that the role of Lollipop ladies was to give out lollies. Shame!— Helen
- 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 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
- I used to think that broccoli was a shrunken-down tree,Anon