Stop Me If You've Heard This One Before

A man's driving through the countryside and his car breaks down. He goes up to the nearest farm, and asks if he can use a phone to call for a towtruck (this joke worked better before cellphones, but play along). The kindly farmer shows him to the phone. After he arranges the tow service, he's got about 30 minutes to wait before help arrives, so he gets to talking with the farmer.

"This is a really nice plot of land you've got out here, friend," he says.

"Oh, this ain't nothin'," replies the farmer. "If you really wanna see somethin', come 'round to the pigpen." And with that, the farmer heads to an enclosure of pigs. "Now, watch this." The farmer whistles, and one of the pigs separates himself from the pack and hobbles over, on three good legs and a peg. The farmer claps twice and the pig rolls over.

"Wow!" says the man. "I've never seen anything like that before!"

"That ain't nothin'," says the farmer. "Watch this." And the farmer snaps his fingers, at which command the pig rears up on its one good hind leg and its peg leg, and takes several steps toward the two men.

"Oh my god, that's incredible!" exclaims the traveller.

"Oh, that ain't nothin'," says the farmer, and then he calls out, "What's two plus two?" and the pig taps its peg on the ground, once, twice, thrice, four times.

The man can't believe his eyes and says, "That's the most amazing thing I've ever seen. No one will ever believe me if I tell them. A trained pig that can add! But, I have to ask.. what's with the peg leg?"

"Oh, well," says the farmer, "a pig that special, you don't eat all at once!"