Being a midwestern guy, when I went to school years ago I was shocked to hear people offer me a "soda" to drink. I thought to myself, "why would I want soda, isn't that something you put in wiskey?" I then found out that these easterners were actually talking about "pop". You know, coke, 7Up, sprite - pop.
Well, it turns out this is a very regional thing. And by the looks of the map, almost as divisive as red vs. blue politics!