I used to believe that in the some "You owe me an IOU" by Hot Hot Heat that the lyric
"You owe me an IOU"
was actually
"Don't go to pacoville"
One day I heard a guy say "Lets go to pacoville!" to his dog.
you can imagine my reaction.
A childhood belief about misheard lyrics

others believed things like this
- I used to believe that the heat from the furnace came from hell, and that it was a straight drop there.Anon
- I used to think what heated the food in the pan was the boiling water, not the heat under it.— Mario
- 'I've got candy in my ears tonight, baby'.
~Canned Heat, Jimiroquai.— Nin - I thought that cold was an actual, positive force and not just the absence of heat— terberous
- I always wondered why shepherds washed their socks by night. (correct lyric: watched their flocks)— MaggieNJ
- A common misheard lyric in BMTH’s ‘Shadow Moses’ is “THIS IS SANDPIT TURTLE!”— Oli