I used to always think as a kid that the song "Blue Bayou" was really "Blue By You" and when that song came on the radio I would always try to find something blue near me.
A childhood belief about misheard lyrics

others believed things like this
- You know the eifel65 song "Im blue da be da ba di"
I thought he said "I'm blue I'm in need of a guy"— Anna - The song "Reverend Blue Jeans" turned out to be "Forever in Blue Jeans." Who would have believed that?— music lover
- Eifel 65 - Blue
I'm Blue (if I was green I would die...)
[I'm blue, da ba dee, da ba di.]— Matt - I used to believe that TV finished after Blue Peter.— Jen
- I used to believe the sky was green and everybody was colorblind since they said it was blue— IM COW
- I used to think that blood was blue until it touched air.— paetrw