Two rednecks, Bubba and Cooter, decide to go to college. Bubba goes first, and he is advised to take maths, history and logic.

-- "What's logic?" says Bubba.
-- "Well, let me give you an example," says the professor. "Do you own a tractor?"
-- "Sure do," says Bubba.
-- "Okay. Then I assume, using logic, that you have a yard."
-- "That's real good," says Bubba, in awe.
-- "Logic also tells me that since you have a yard, you also have a house. Is that right?"
-- "Gawly!” says Bubba.
-- "And since you own a house and a house is tough to take care of by yourself, the odds are that you have a wife. Right?"
-- "Betty Mae! This is incredible!"
-- "Finally, since you have a wife, logically I can assume you are heterosexual. Is that right?"
-- "You are absolutely right! Why that's the most fascinatin' thang I ever heerd of. I can't wait to take this here logic class!"

Bubba, proud of the new world opening up to him, goes back into the hallway where Cooter is waiting.
-- "So what classes are ya takin’?" says Cooter.
-- "Maths, history and logic," says Bubba.
-- "What in tarnation is logic?"
-- "Let me give you an example," says Bubba. "Do you own a tractor?"
-- "No."
-- "Then you’re gay."