During the "Bang! Bang!" part of the song Love Shack by the B-52s I thought that the backup singers were actually yelling "Batman!"
I was 4 and just assumed that the song must have been on the soundtrack for the Batman movie. I also thought that the guy who played the Joker (whom I now know as Jack Nicholson) was the guy who sang in the song. Man I was way off on that one. Jack Nicholson has to have SO much more money than them!
A childhood belief about misheard lyrics

others believed things like this
- I thought when the Big Bang happened it made an actual bang noise— Catte
- I used to believe that the B-52's song "Love Shack" was actually "Love Shark!"— Natalie
- That the "Childcatcher" from Chitty Chitty Bang Bang would come up the toilet + catch me while I was on it.— Kat
- When I first heard Bruce Springsteen's song, "Born in the USA," I thought that the song was "Porn in the USA"Anon
- i thought I got one year older when my family sang the birthday song.— I am the ghost
- In Beyonce's song 'Crazy in Love', I always thought she said 'Daisy right now'.Anon