In the 80's, in my early teens, I used to think that one line of the lyrics in "The Final Countdown" by Europe was "We're heading for peanuts" - when it's really "We're heading for Venus"...
A childhood belief about misheard lyrics

others believed things like this
- I thought venus fly traps are from the planet Venus— Ted Snow
- I used to believe that Venetian blinds came from Venus.— Valerie
- I used to believe that if you put your hand in a venus fly trap it would eat it.Anon
- I used to think that Bananarama's song "I'm You Venus" was "I'm Your Penis"Anon
- I believed a star that I later found out was the planet Venus was the Tooth Fairy— Jillybean
- i thought chickens laid peanuts.
— pikl