Quick Google Check: "Southernisms" brings up 21,000 search results. "Northernisms" brings up 10,000. Why the big difference? Northernisms don't exist, they're just what things are called. Moving down south has required me to decipherer another language entirely
Soda vs. Coke - OK, before I get going on this one, as a northerner, I do reject the common northern term, "Pop". In Wisconsin, we say "Soda" and have no clue why all our surrounding states say "Pop". Pop just sounds like a ridiculously outdated term from the '50s, and saying it further emphasizes the dreaded Fargo accent. That said Soda, Pop, and Soft Drink are all vastly superior than Coke. It seems like southerners picked the most generic term, and used it for everything it remotely resembles. If I ask for a Coke, I don't want the waitress to ask me "what kind of coke do you want?". Do I really have to say "Regular" or "Coke Coke"?
All said, the language of the South is just something I've had to learn. I work with clients that continually correct me when I say "You Guys". Sometimes I even catch myself throwing out the occasional "Ya'll". Still, if there ever comes a day when "Fixin' to", "All Ya'll", or "What in tarnation" become a regular part of my vocab, I'm catching the first Greyhound up I-55 north.