I have a cousin who works in the police force, once when he was searching someone's home he asked another officer to search the "Chester drawers" - apparently he never knew people actually said "chest of drawers" until he was corrected that day.
I remember I used to always pronounce the word "temporary" as "tempowary". It's strange how we can get these things wrong for years at a time, you'd think people would correct us much sooner than they actually do.
I wonder if this sort of thing has happened to many other people, and if so what did you get wrong? And how long did it take before realised you were making a mistake?