My favorite variant of the joke:

Two hillbillies are out in the woods, sitting on tree stumps, drinking beer and shooting the shit, when one of them yells in pain. He jumps up and slaps aside a rattlesnake that bit his ass, then collapses to the ground, screaming in pain.

The second hillbilly quickly calls 911 on his cellphone.

"Hey! My friend Billy-Joe just got bit on the ass by a rattlesnake!" He says. "We're ten miles away from civilization! Can I save him?"

The 911 Operator replies, "If he was just bitten, sir, you can still save him. Take off his pants, make a small incision on the wound, then suck the poison out with your mouth and spit it on the ground."

The hillbilly nods and hangs up. He turns to his friend and sighs.

"Sorry, Billy-Joe. She says you're gonna die."