On the song Psycho Killer by Talking Heads he says "Psycho killer, Qu'est-ce que c'est" (French for "what is it?") I thought at first he was saying "Psycho killer, kiss Casey" and I wondered who Casey was and why the psycho killer would kill him/her
A childhood belief about misheard lyrics

others believed things like this
- When I was little, I used to think that a serial killer was a killer who ate a lot of cereal.— believe
- The first time I hear about a serial killer, I laughed. You can't kill cereal. It's not alive.Anon
- I thought that my dog was a killer dog that was undercover and that he was like a spy or something— Laura
- when i was little i thought a serial killer was someone who killed people for their cereal— emily
- I used to think i was a serial killer because i ate cereal!— Mikita Jones
- I used to think a serial killer was golden grams...— weird