Until I was about 8 I thought the Christmas song that says "Gloria in excelsius day-o" [or however the crap you spell it xP] said "Oreo".
Didn't make sense to me at the time why in Christmas songs they'd be singing about Oreos, but I just assumed...
A childhood belief about misheard lyrics

others believed things like this
- I was told that for every christmas carol i sang before christmas time santa would give me one less present!— K
- I use to think the known Christmas song "in excelsis deo" was en chelsea's dayo— Mike Simmons
- I didn't know Reindeer existed, I thought they were just christmas animals for storiesAnon
- "Christmas time
mistletoe and brine..."— Santa Puncher - We didn't have a chimney in our house. Father Christmas had to come in through the letter box.— Ginnean
- when i was little i thought that jesus delivered presents on christmas not santa .— gaby