My little brother (he's 5) sings the chorus from the Jimmy Eat World song "little biddle in the middle exercise" instead of little girl you're in the middle of the ride."
He will still argue with you if you try to correct it.
A childhood belief about misheard lyrics

others believed things like this
- When me and my brother were kids we used to think that Jim'll Fix it's Jimmy Saville was called Jim'llAnon
- I used to believe my middle name was and. At age 12, I discovered that it was actually "ann".Anon
- I used to think that the chorus of "mountain song" by jane's addiction was in a different language— nothing'sshocking
- I used to believe that my middle name was Goofy, even though it's actually Margaret.— Lisa
- I used to believe that everyone had the same middle name as me... Elizabeth.
(even my uncles)— K.O. - I used to believe that the red thing in the middle of a Greek olive was the pit.— Liz