So what do you call a carbonated beverage in a can? Pop? Soda? Cola? Coke? Check this map on the distribution of various names for carbonated can beverages around the country. I grew up in Memphis, TN, and, indeed, we refered to all carbonated beverages as, "Coke."
"Bring me a Coke" translated into, "Bring me something cold. carbonated and in a can or bottle." The only exception to the "Coke" designation was "RC Cola," which was alaways asked for by name, except that the "R" was pronounced "are-ah," almost like "aura," and the "C" with a hard tounge tucked flat against the lower teeth and the "C" almost hissed out, like "seize". "Gimme one of them aur (pause) aa-seizes." The length of time for the pause between aur and aa was a function of 1) how far back in the Delta you were actually from, and 2) how cool you wanted to appear. Southern funnyman "Brother" Dave Gardner would always roll the aur for a laugh: "Aur aur aur aur aur aa-seize!"
Also, by law, when ordering an R.C. Cola, you also had to get a Moonpie. You could shorten "moonpie" to "'pie," but that was more of a local aberation than a widespread subset. That particular combination of cola/pie, BTW, has been called the "Dixie Duo," and, yes, you can get the t-shirt.
Thanks to Jeff Jacoby at the Boston Globe!