I had no idea what a “pufferbelly” was for an embarrassingly long time. The closest thing I had as an idea for what it meant was that a “pufferbelly” was some kind of humanoid, due to the Wiggles performing the song. It was only until I was in my mid teens that I had to be told they were steam engines!
A childhood belief about misheard lyrics

others believed things like this
- I used to think being engaged meant being in jail. I have no idea how I came to that conclusion.— CNB
- when i was little i asked what time midnight mass started.
i honestly had no idea.— what time?? - last time when the television was on i thought the people were performing in it -.-
— irritated kid - I used to believe that car exhaust pipes were what propelled cars, instead of the engines.— Thomas Johnston
- Up until 5 seconds ago, I had no idea wat a gherkin was— It's a little cucumber, stupid!
- I used to think Hungary and Turkey were the same country... I have no idea where that came from...— Skylla