When I was little, I thought that Spanish and Italian were the same except Spanish was good and Italian was evil. I probably got this belief because the only Hispanic people I knew of were always friendly to us and would never hurt anyone, while my only knowledge of Italian people was scary, ruthless gangsters from DVDs and books my parents had.
When I was little, I saw a picture of Mafia gangsters in a book and thought they were Spanish instead of Italian.
I used to think that Psy and Kim Jong-Un were the same person
I used to think Cancun was Camp Coon
I used to think that Hebrews came from the Hebrides.
When I was 5 years old, I used to believe Poland was snowy and cold all year round, like the North Pole.
I used to think that the little people used in population charts represented just one single person, and wondered how they could count every specific person living in every country.
I used to believe all Italian women were named Mia because of the phrase "Mamma Mia!"
I thought a Prime Minister was some kind of religious leader, due to the "Minister" part
I used to think the word barber was related to the word 'Berber', like Turks and North Africans being Semitic people, and Turkish guys being into male hairdressing.