I had never heard the german version of Oh Christmas Tree (Oh Tanenbaum) until I was 18. I was walking in a dept. store with my brother and we both were positive they were saying "Oh Timebomb". It made no sense for a christmas song but every time they said it we heard timebomb.
A childhood belief about misheard lyrics

others believed things like this
- I used to think that partridge in a pear tree was "cartridge" in a pear tree(christmas song)— Erica
- 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 used to believe that broccoli grew on trees. It looks like a tree, so it made sense, right?— Catherine...
- I used to believe reindeer made it rain because for many years it rained on christmas eve night.Anon
- "Christmas time
mistletoe and brine..."— Santa Puncher