Since Jefferson Davis was part of the US Civil War, that's understandable, but I thought Jeff Foxworthy was well-known for his "You might be a redneck" jokes..."If your family tree doesn't fork, you might be a redneck," "If you think loading the dishwasher means getting your wife drunk, you might be a redneck." etc.
Also never heard of the redneck comedian, but being British that's probably not too surprising.