Even as a kid I liked classical music, but was convinced that all operas were written in Spanish. Well, I knew they weren't in english, and what with Carmen's bullfighters, Barber of Seville, Don Giovanni, Don Carlos and others it seemed logical. I could never work out "Figaro" though - Figaro was Gepetto's cat in the Disney film "Pinocchio", and never sang a note in any language that I could remember.
At least I did better than the little lad who, when asked by his operatic parents what his favourite aria was answered, "The one about elephant's ears". This puzzled them for ages until they heard "La donna e mobile" from "Rigoletto", by a singer also with poor knowledge of italian - catch the last line -yep, easily taken for "elephant's ears"!
A childhood belief about misheard lyrics

others believed things like this
- I used to believe that Spanish and Italian were the same language;Spanish was for boys and Italian for girlsAnon
- I used to believe that foreigners' ears translated English words to their own languageAnon
- i used to believe that if i didn't work at school, i would have donkey ears, so now i work hard !!!— denis
- I used to belive that if I put my finges in my ears when i sang noone could hear me— Helen
- I used to believe that my dad use to find magic balls behind my ears and catch them in a paper bag.— Netty
- I used to think that adults spoke an entirely different language (not English) when kids weren't around. — Swordfish