Up until I was like 7 or 8, I thought the lyrics to the song "Last Christmas" were, "Last Christmas, I gave you my harp..."
I used to listen to this song at school, and the lyrics were things like "Welcome back" and "We're proud of you". I thought it was about a girl (no idea why I specifically thought she was a girl) graduating a boarding high school, and it was sung by her parents.
Later, I learned that it was about welcoming soldiers back after a war, but I thought my version was better.
When I was a child, I used to believe the singer or the music group lived in my CD's and they allowed to sing (and live) only when I wanted.
My cousin used to think that a group of nine singers was called a "niner".
"Achy Breaky Heart" by Billy Ray Cyrus was popular when I was a kid. However, I misunderstood the line "He might blow up and kill this man." I thought "this man" was referring to some other specific man - in short, that his heart would explode so violently as to cause collateral damage.
I thought Total Eclipse of the Heart went "nothing I can see, total eclipse of the sun".
I thought the "physically fit" lines in the song "I Like to Move It" were "fizzy coloured feet".
When I heard the song "Oh Susanna" as a very little kid I was very confused about the verse about coming from Alabama with "a banjo on my knee".I literally thought it meant the guy had limped a long distance with a banjo tied or strapped to his knee, which must have made his knee really sore and raw! My belief in this idiotic idea was further confirmed by my grandmother who for some reason didn't think it was very Ladylike to play a banjo.When she heard me singing the song ( we learned it it school) she commented sharply that she hoped she would never see me with a banjo on my knee.I quickly agreed with her.Who wanted to do anything as stupid and painful as to strap a banjo on my knee and go hiking to another state until my skin rubbed off? It was several years before I figured out the actual meaning of the song and the snobby attitude behind Grandmother's comment.
When I was young I did not asscociate the Danny Boy song with Scotland, and with the words "... the pipes the pipes are ca-alling"; the image I had was of vague industrial water pipes - and wondered why someone was being called by them, but song lyrics were often pretty strange, so I just left it at that.
I used to think that the lyric "boiled or stewed, whole or chewed" in Cookie Monster's healthy food song was "almond stew, polo chew".