Etgar Keret is a great short story writer whose work is all the greater because it's funny. There is, of course, room in the house of fiction for comedy, but in the little lean-to annexe that accommodates short stories, the sound echoing from within is rarely a hearty, back-slapping "Ha ha" but more often a deep, throaty, brow-furrowing, chin-stroking "Hmm". There are not a lot of laughs in any list of the world's great short stories  Hemingway's "Hills Like White Elephants", Shirley Jackson's "The Lottery", Kafka's "In the Penal Colony", "The Fly" by Katherine Mansfield. Borges. Julio Cortázar. Ingeborg Bachmann. This may be because, as it approaches the horizon of its capacities and capabilities, the short story inevitably begins to resemble a kind of biblical narrative, a fable, a wise saying. If it approaches the condition of a gag, it's annoying; we expect better of it. Think of Mark Twain's "The Celebrated Jumping Frog of Calaveras County". Shaggy dog stories, jokes and anecdotes are what people tell each other in a pub; an author is expected to grow out of them. In Reading Chekhov: A Critical Journey, Janet Malcolm makes the troubling observation that "Chekhov began to show signs of becoming Chekhov only when he turned his hand to writing short fiction that wasn't funny". It's certainly true of Chekhov, but then, thank goodness, we're not all Chekhov. In contrast, bucking the trend, proudly riding once again on a big black shaggy dog, comes Etgar Keret, who most becomes himself in comedy shorts, telling tales of the absurd and the surreal.

The new book's title story, "Suddenly, a Knock on the Door", sets the tone for the whole. The unnamed narrator is being held hostage by a group of people who are demanding to be told a story  "I bet things like this never happen to Amos Oz or David Grossman." The narrator tries to fob them off with a story about a man being held hostage in a room with a bunch of people demanding to be told a story. But they've heard that one before. "That's an eyewitness report. It's exactly what's happening here right now. Exactly what we're trying to run away from. Don't you go and dump reality on us like a rubbish truck. Use your imagination, man, create, invent, take it all the way." And so Keret does.

In "Lieland", Robbie visits the place where all one's lies exist. "Once, when he was two hours late for work, he'd made up a lie about a German shepherd he'd found sprawled out beside the road ... In this lie, the dog was paralysed in two legs, and he'd taken it to the vet only to find that the dog was never going to be able to move his hind legs again ..." Robbie then meets the dog from his lie, recognising it at once "by the way it half crawled forward, its two forelegs struggling to pull its paralysed pelvis along".

In "Unzipping", a woman called Ella is lying in bed with her lover, Tsiki. "She could tell he was hiding something. And sure enough, one night, taking advantage of the fact that he slept with his mouth open, she gently slipped her fingers under his tongue  and found it. It was a zip. A teensy zip. But when she pulled at it, her whole Tsiki opened up like an oyster, and inside was Jurgen. Unlike Tsiki, Jurgen had a goatee, meticulously shaped sideburns and an uncircumcised penis."

The stories are all thought-experiments. What if, they ask. Why not? And, what the heck? Like all art, they are highly patterned, highly charged, refracted reflections on the chaos and randomness of everyday existence. In "Cheesus Christ", for example, a man goes into a cheeseburger restaurant called, naturally, Cheesus Christ, and which serves only cheeseburgers, and asks for a burger without cheese. He gets stabbed, and the CEO of the resataurant resigns, retiring to a beach in Brazil, where he sends an email. "As he pressed 'send', his finger touched the wings of a butterfly sleeping on the keyboard. The butterfly fluttered its wings. Somewhere on the other side of the world, evil winds began to blow." As one of the 20th century's great comic writers  and one of Keret's true precursors  might have said, so it goes.

Sometimes, admittedly, it goes so that the reader begins to tire of so much relentless wit and invention. "There's a theory," begins the story "Parallel Universes", "that says there are billions of universes, parallel to the one we live in, and that each of them is slightly different." Slight differences can sometimes begin to sound the same: the story of a magic goldfish ("What, of this Goldfish, Would You Wish?"); the story of a haemorrhoid that suffered from a man ("Haemorrhoid"); the story of a story that rewards attentive readers with a brand new Mazda Lantis with a metallic-grey finish ("The Story, Victorious"). But then again, to complain about Keret being Keret is like complaining about Chekhov being Chekhov. Let's indulge him. The story "Shut" begins, "I know a man who fantasises all the time." Me, too.

 Ian Sansom's Mobile Library Mystery Series is published by Fourth Estate.