When I was little I used to think that the song by The Mamas and the Papa's titled "Mama Cass" was "Mama Cat". I still do not know why.
I also used to think (about 2 years ago when I was 10) that the modern pop song where there was a line that said "chicks in Maui" was 'ticks in my wee", and I already think you know what I mean!
A childhood belief about misheard lyrics

others believed things like this
- My mother's name was Anna. She was called "Annemor"(Duck mama). I was convinced I was a duckling.— Christine Norway
- I used to think that the song"Stayin Alive" said "Staying In Line" like at school when I was little. — MacKenzie
- I used to think that the line in the song "Life in the Fast Lane" was "Fights in the Bat Plane".Anon
- When I first heard Bruce Springsteen's song, "Born in the USA," I thought that the song was "Porn in the USA"Anon
- i thaught the michael jackson song billy jean song said Janet's not my son Anon
- i thought the line "saving my face" from the KT Tunstall song of the same name was "shaving my face"Anon