As a generic term, soda. Pop is something you do to a balloon. If I'm ordering at a restaurant then I'll ask for the specific drink.
When I lived in Nashville, it was not uncommon to hear conversations go something like this at restaurants when people were ordering soda. I've always found it funny.
Wait staff: What can I get you for drinks?
Customer: Coke
Wait staff: What kind?
On a similar side note, When I was in NYC (original hometown), I had some business guests from Nashville come up and we went to lunch. And they ordered Sweet Tea. In NYC at the time, don't know if has changed since, it has been like 15 years or so, if you ordered just tea, you would get hot tea, but in the south if you ordered tea you would get iced tea.