The term
redneck refers to a (typically male) person having a red
neck caused by working outdoors in the sunlight over the course
of their lifetime. The effect of decades of direct sunlight
on the exposed skin of the back of the neck not only reddens the skin,
but renders the skin leathery and tough, and is typically very wrinkled
by late middle age.
The term redneck is often but not always pejorative,
in the same sense as hayseed[?].