I thought until I was about 25 that the ZZ Top song lyric, "Slip inside my sleeping bag" was actually "SuperSonic Secret Man". It still sounds like that to me!
A childhood belief about misheard lyrics

others believed things like this
- When I was young,I thought the lyrics "Secret Agent man" were actually "Secret Asian Man".— M.M.B.
- i thought that our cats were secret spies for my parents and i would never do anything bad around them. Anon
- i really thought that "key" was a secret letter to the alphabet that only i knew.— amber
- When I was young I thought that police had soft skin, because this is how it sounds in French " Peau lisse "
— amine - 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