Pop
In the South, for some insane reason, all pop is called "coke". So when I first moved from Michigan to Louisiana I had a fascinating conversation that went like this:
Southern person "Do you want something to drink? We have a vending machine"
Me "That would be awesome. I'd like a coke"
Southern person "Ok, what kind?"
Me "Ummm, just a regular coke"
Souther person "ok but what kind of coke?
Me "Just a plain coke, not diet or anything"
Southern person "BUT WHAT KIND OF COKE DO YOU WANT!!!!!"
Me "ARGGGHHHHH!!!!"