My mom said her last name used to be carter until she married my dad, and it caused me to believe when two people got married they got to make up a new last name together by combining their old last names.
A childhood belief about names

others believed things like this
- i used to believe nuns were married to jesus and priests were married to mary.— sunshine
- I used to believe that a widower was a guy who killed married husbands to make thier wife a widow— Jessica
- i used to believe, that if you were married you were a mum and dad— Fay
- when I was little I used to think you had to have a baby before you got married!— Supergirl
- I used to believe that woman had to pay to keep their last name when they got married!!!!!!!— Imaginative_Kidd
- I used to think I was going to marry my mom, even though my dad was already married to her.— nick