I used to think that in the song written by backsteet boys that goes "there's something missing in my heart" when "There's something disespangdidly so!". I thought disespangdidly was a foreign language that only the backstreet boys knew!
A childhood belief about misheard lyrics

others believed things like this
- I used to believe the Beastie Boys were a boy band. Well, the name sounds similar to Backstreet Boys!Anon
- Backstreet Boys - I want it that way? I heard "I was born on a tidal wave— gembop
- I never knew why boys had to lift up the toilet seat...until my friend told me that boys had bad aim.Anon
- I thought the song "Party Time" by Moby was actually saying "heart attack" (this was before I knew the title)— Elviessa
- I used to think that foreign people coughed and sneezed in a different language.— Even more stupid
- I used to believe, that I am able to speak every foreign language only by learning "their" alphabet.— matej