I don't equate hillbilly with Southerner, I equate it with Appalachian. I thought berdawn was just pointing out our local euphemisms for things. Most people around here outside of the cities and suburbs refer to themselves as hillbillies on a common and unironic basis. Many of them are even proud of it.
I know lots of really awesome hillbillies, and a few real a-holes. I also know a lot of really smart hillbillies.
It's really interesting being considered a liberal hippie way out here in staunch Mountain Dew/Marlboro/uber-conservative country. Leads to a lot of unusual conversations.
Most hillbilly English is derived from Elizabethan English, or older, as well as Scottish. Many hillbilly turns of phrase can be found in plays by Shakespeare.