"So I went out and bought me a jorō (hooker) last night."

"Oh yeah? Where'd you go?"

"To the Matsuba."

"Who'd you buy?"

"Somenosuke."

"What? You know Somenosuke?"

"Sure I do. Great guy."

(It's funny because the first speaker has never actually bought a jorō at all, which embarrassing character flaw is exposed by his ignorance of their naming conventions: he thinks that they use male names because they are men, rather than because that's just what jorō do.)

"Damn, this nosebleed just won't stop," said the first man.

"Here. I know what to do," said the second. He pulled three hairs out of the back of the first man's neck [which was widely believed to cure nosebleeds because it was a sudden painful shock].

Then the first man turned into a monkey.

(It's funny because back in the Edo period there was a saying that humans are only one or two three hairs away from monkeys, with humans being the hairier ones.)

Okay, now one that's less opaque:

A country bumpkin came to stay with a city-dwelling friend who loved kemari. They ate a light lunch together and then the urbanite said "All right, now let's get stuck into the main course!" and brought out a ball.

"Thanks!" said the bumpkin, took it from him, and started gnawing at it.

"No, no, no! Mōshi! Dude!" said the other man. "Here, let me show you." And he took it back and started kicking it into the air.

"Ah, of course," said the bumpkin. "I thought it needed tenderizing."

(It's funny because bumpkins are ignorant of the important things like playing hackey-sack, because they waste all their time on growing food for city-dwellers to eat.)