Coke here too - I think it's because Coke was invented - and was the reigning monarch for so long - in the south, it became the generic term for any soft drink. Sort of like having a Eureka hoover (if you live in the UK), a Cannon xerox machine, a Maytag frigidaire (that one may be southern too), Chapstick, Kleen-ex, Weed-eater...you get the idea
Writing from beautiful Chattanooga, TN - home of the world's first Coca-Cola bottling company (even though it was invented in Atlanta)

