The song Puff The Magic Dragon made me kind of cross, at their fleeting reference to their friend "Frolicton the Ottomist". I didn't know what an Ottomist was, and wished the song would go into more detail.
It took me a few years to work it out.
A childhood belief about misheard lyrics

others believed things like this
- The buckinghams song "kind of a drag", i always thought they were singing, "Canada Dry"— bobbybobby
- When I first heard Bruce Springsteen's song, "Born in the USA," I thought that the song was "Porn in the USA"Anon
- i thaught the michael jackson song billy jean song said Janet's not my son Anon
- I used to be very fascinated by the weather and sometimes wished I could have a tornado for a best friend.— Will
- In the song "We're going to Ibiza", my friend thought they said "we're going to eat pizza"!— Smaranda
- i, too, thought my grandma made up the bushel and a peck song. :)— nessa