There probably isn't anything more southern than sweet tea. In high school, I worked at a restaurant that literally made large garbage can sized batches daily. The servers would swing into the kitchen and dunk a pitcher to keep the endless refills flowing! One of the culture shocks I experienced when moving away from the south was the lack of sweet tea elsewhere. Sure, you can order an iced tea and doctor it up with a packet of sweetener, but it just isn't quite the same. If you come to visit me, you can pretty much bet on being offered a glass of sweet tea (or honey lemonade).