I thought that in the song "Hollaback Girl" by Gwen Stefani it said "i'm not in no Hall of Fat Girls" when it really says "i'm no hollaback girl". I figured out my mistake when I found out what the name of the song was and realized thats what it had been saying all along.
A childhood belief about misheard lyrics

others believed things like this
- When I was younger, I saw Madonna's video for "Material Girl". I thought she was singing "I'm a Cheerio Girl"!— Greg
- I always thought instead of saying "Im a material girl" Madonna was saying "Im a cheerio girl".— Tiffany
- When I was a little girl, I believed that all cats were girls and all dogs were boys. :)— Mary Ellen
- When I first heard Bruce Springsteen's song, "Born in the USA," I thought that the song was "Porn in the USA"Anon
- I used to think it was true that only ugly girls poop and I thought I was an ugly girl because I poopedAnon
- I used to believe that the words to Michael Jacksons "Liberian Girl" were "librarian girl".— Paul