Robert Fisk: Heard the one about the child and the blood money?

The book bazaar stands just opposite the main gates of Tehran University, a line of "libraries" of Persian poetry, American obstetrics manuals, English literature and novels translated from Russian, French and Italian authors.

It's a good place to while away a hot afternoon – far from the ladies and gentlemen of the Ministry of Islamic Guidance. This used to be a place of tear gas and stones and government thugs smashing their way into university dormitories after the presidential elections which Mahmoud Ahmadinejad won – or did not win – in June of 2009. Now it's a place to sup of the cream of education, to understand the Iranian desire to learn, to prowl the books.

I buy a volume of 100 years of Persian poetry and another, smaller work by Fereydoon Moshiri. "All the sparrows/blaming me in your absence,/keep calling your name." I buy a comparatively new Oxford translation of Chekhov's About Love and Other Stories, some of which I have read before, but now I realise why Chekhov is so popular in Iran. His stories and plays capture all too well the doomed pessimism of a society whose fate is inevitable, of individuals whose fates are equally predestined. Chekhov's Gusev fits the necrocracy element of the Iranian regime rather well, its protagonist – a dying Russian serviceman, taken sick on his journey home from the Far East to Odessa – confiding to us his last memories.

He dies, and is thus buried at sea inside a weighted sailcloth. "The sailor on duty lifts the end of the board, Gusev slides off it, plunges head first, somersaults in the air, and – plop!... After he has travelled about eight to ten fathoms, rocking gently from side to side ... he meets a shoal of little pilot fish. When they see the dark body, they stop dead in their tracks, then they suddenly all turn round and disappear... Then another dark body appears. It is a shark ... The shark teases the body a little, then nonchalantly places its mouth underneath it, carefully grazes it with its teeth and the sailcloth is ripped along the whole length of the body from head to toe; one of the weights falls out..."

I reread The Lady with the Little Dog, its mournful, utterly credible, tawdry yet deeply moving love affair – Persian stories are a bit like this, all about longing and unfulfilment and desire – captured perfectly in Rosamund Bartlett's translation. "And it seemed that in a little while a solution would be found and then a new, wonderful life would begin, but it was clear to both of them that the end was still a long way off and that the most complex and difficult part was only just beginning." Thus the story ends, and I am always left asking Chekhov, like a child, "Sure, but then what happened, for God's sake?" Because these adulterous lovers must be human, historic figures who once lived in Tsarist Russia, perhaps known to the author himself, as substantial as Gusev's corpse. That is the gift of Chekhov. Fiction becomes reality. It happens in Iran all the time.

It is a relief to buy my last book, 300 Delightful Jokes, compiled by Seyyed Mashallah Alipayam, published in Tehran, primarily as an English reader. On its cover are drawings of a slightly bearded young man, a woman in Islamic head covering and a laughing boy. The legend beneath tells me that "Laughter and humour are good for your health". I have no argument with this, until I flip open page 96 to be confronted by the following: "Would you like your father to die so you would inherit his belongings?" they asked a naughty child. "I would like someone to kill him instead so I would receive blood money as well as inheritance," he replied.

I literally gasp. Jokes? Humour? I turn the pages to a joke intriguingly entitled Wine: "The devil went to a young man's bedside in a hideous form. 'I am death,' he roared. 'And if you want to be saved, you will have to perform one of these three alternatives: either you kill your old father, strangle your sister to death or drink a few mugs of wine.' 'I cannot commit such crimes against my father or sister,' the young man said shaking with fear. 'But I can drink some wine.' Then he drank mug after mug and in his drunkenness, the young man killed both his father and sister."

Now I hate the word, but that really is a gobsmacker, isn't it? Laughter and humour are good for my health. Maybe this is a warning against alcohol (a substance much in evidence in old Persian poetry and art), but I rather think not. "One day a fly told a spider: 'Look at your arms and legs. They are so slender and thin!' 'You will see how dark the world is once you get caught in my web,' the spider replied."

Then there's the really awful: "'Please Mr Notary! I want to divorce this woman.' 'But you only got married yesterday. Why do you want to divorce her today?' 'Obvious! Yesterday I wasn't wearing my glasses.'" There's more in this vein. What am I to believe? There are things here in this cheap little book that worry me. Is this Iranian "humour"?

Then that night I attend a foreign ministry banquet hosted by Ali Akbar Salehi, the minister himself. As I queue to leave, behind a long trail of diplomats from "friendly" nations – I find myself cheerfully greeted by ambassadors of all kinds of unsavoury regimes – I spot an African diplomat in a magnificent floral dress. She walks up to Salehi to say goodbye. And holds out her hand. "If I shake your hand tonight," the foreign minister of Iran replies, quick as a flash, "I won't be foreign minister tomorrow morning!" Humour is good for your health...