Hillbilly Girl

Listen up, you chucklehead. This joke is banking on the stereotype that hillbilly families, especially rednecks, tend to, uh, get a little too close for comfort. So, the punchline implies that if a hillbilly girl is faster than her brothers, she's a "redneck virgin" because she can outrun their incestuous advances. Get it? It's funny because it's icky! Also, you probably wear Crocs in public.