This Terrible Redneck Joke

It is funny but an awful pun. As you can read, this pun refers to one of those redneck stereotypes. The wordplay here is on the word "period." It relates to both menstruation and hockey intervals. As you may know, the game hockey is composed of three periods. This joke states that a hockey player takes a bath after three periods (game) and a redneck girl probably doesn't shower even after three periods (menstrual cycles.)