When we were little, my brother sang "Volare," at top volume with the lyric "Oh-Lah-Tay." He sang it all summer and nearly drove the family nuts.
I spent much of my childhood wondering what a "donserly light" was in the Star Spangled Banner.
A childhood belief about misheard lyrics

others believed things like this
- Billy Squire sang about "My Kind of Lover". My wife sang about "My Candelabra"— Wailerman
- i thought I got one year older when my family sang the birthday song.— I am the ghost
- I spent ages wondering what a bart ender was as a child without realising that it was actually bar tender.— Heather
- I used to believe that at the beach town where we spent the summer, they took the sidewalks in for the winter.— Missy
- Even though the title is 'How Bizarre', I always thought he sang "help is on"...Anon
- I used to belive that if I put my finges in my ears when i sang noone could hear me— Helen