Well I'm from Illinois and when I moved out here to Boston, it was a whole new language! I was used to soda, pop, and soda pop (sodie pop if you say it like Andy on Andy of Mayberry). My first day of work here, a birthday party was being planned. Everyone was already bringing necessary food dishes so I was told to bring the tonic. I asked, "Oh, we're going to have gin and tonic during work time?" I was stared at with no answer. In my head I thought "She doesn't mean hair tonic, does she?" The eventual response was, "Bring a 2 liter of Diet Coke".
Then it was learning:
Illinois vs Boston:
Washrag vs facecloth
liquor store vs packie
grocery shopping vs food shopping
milk shake (has ice cream in it) vs milk shake (is shook milk)
basement vs cellar
lunch vs dinner
rubber band vs elastic
I am sure there must be others but who cares.. Tonic was and still is the most baffling to me (but I SAY it regularly now!) And no ice cream in a milk shake!