When I was little, I thought the lyric in The Beatles' "Something" that goes, "I don't wanna leave her now / you know I believe and how" went, "I don't wanna leave her now / you know I believe in cow."
My mom had recently explained to me that George Harrison practiced Hinduism, thus I thought it was perfectly logical for him to write a song about a cow.
A childhood belief about misheard lyrics

others believed things like this
- I used to sing at the top of my voice "OLD GIRLS JUST WANNA HAVE FUN"— claire
- in the song "show me heaven" i used to sing "make me breakfast" instead of "leave me breathless"Anon
- when i was little i thought that toys had parties wee little partys when you would leave home— Dominique Tello
- When I was younger I thought that the jets that leave lines in the sky were rockets — Harry
- When I was young, I thought that the smoke that jets leave behind them was how clouds were formed. — Rebecca
- I thought "Angel of the Moring", by Juice Newton said "just brush me teeth before you leave me"!!!Anon