It's USA humor, about people that live out in the boonies, swamps, deep in the mountains or trailer parks.
This link might help.
_http://www.countryhumor.com/redneck/mightbe.htm
I like these,
"You might be a redneck if"
"You consider a three piece suit to be: a pair of overalls, a plaid flannel shirt and thermal underwear."
"Your idea of a 7 course meal is a bucket of KFC and a sixpack."
"Your wife has ever said, "Come move this transmission so I can take a bath.""
"Your mother has been involved in a fistfight at a high school sports event."