I used to believe that Leona Lewis' song "Angel" was about a ninja, because of how she pronounced the word.
A childhood belief about misheard lyrics

others believed things like this
- I used to believe that "Meningococcal" was pronounced "Ninja cockel."Anon
- I used to think that the Huey Lewis and the News song "I Want a New Drug" went "I Want a New Truck".— Chloe
- When I was little I used to believe that comedian Jerry Lewis and rocker Jerry Lee Lewis were the same person.— Paul
- When I was young I used to think that WHSmith was all one word, and was thus pronounced "Wwwhhhhuuusmith"— Nathan
- I used to believe that the word 'circumstances' was pronounced 'circus dancers'.— Mel
- When i first saw the word "Czech" somewhere, i pronounced it "siz-ETCH" in my head — Pachisu