There is a very real linguistic and cultural difficulty involved in writing about Francis Veber's excellent little comedy Le Dîner de Cons. And that is how, precisely, is one to translate the word "con"?

The subtitles for this movie try, variously, "fool", "idiot" and "asshole" - not entirely evasions these, by any means, but neither do they come to the point. Sartre had something more astringent in mind, surely, when he famously called AJ Ayer a "con". My old Faber edition of Waiting for Godot, in Beckett's English version, has the line Les gens sont les cons rendered as "People are bloody ignorant apes", a translation that presumably pleased the Lord Chamberlain, if no one else.

But cunt isn't quite right either. Its direct aggression, for so many the terminus of the Insult Line, does not generally convey the distinctively comic sense of con and the sense in which it is used in Le Dîner de Cons. Here it has the tone of exasperation, of despair, of abject and impotent complaint that people can be so stupid, together with an outraged suspicion that their stupidity must have an element of semi-intentional malevolence, for which simple, rational decency demands a rebuke. Con! shouts this film, con! con! con!, flapping its arms in distress at sheer impoverishment of intellect detectable in so many people, and the casual, unthinking insult this represents to the rest of us.

This film, adapted by Veber from his stage play, is about a dinner of cons organised by a wealthy and fastidious publisher, Pierre Brochant, and like-minded male friends: the premier rank of Paris society. Every Wednesday, they have a "dinner of fools", to which each must bring a con as a guest, an appalling and grotesque imbecile, and the poor dupe must remain in ignorance of the reason for his invitation. Throughout the evening, his hobbies and opinions will be heard with flattering reverence and attention. When they have all gone, this sinister society discusses its candidates with passionate connoisseurship, deciding who has brought the biggest con and gleefully awarding the palm. Each member is as keenly competitive and proud of his nominee as the Fellow of an Oxford or Cambridge college might be about bringing in a Nobel laureate as his guest at high table.

Veber's Dîner de Cons is a compellingly unpleasant secret theatre of cruelty, and it is also, unexpectedly, extremely funny. As the film begins, Brochant is beside himself with dismay. He has no con to bring to that week's dinner, and expects to be trounced by someone who is bringing along a man whose hobby is collecting boomerangs. The opening shot shows the guy throwing his boomerang in the park, answering the mobile phone call inviting him to dinner, then naturally getting knocked out by the returning boomerang. A con of the first water.

But then Brochant is saved. A friend alerts him to the existence of one François Pignon, a clerk at the finance ministry who has devoted his life to making matchstick models of great public buildings. An ugly, bald, cheerful little man. He is an awe-inspiring con, a con and a half. Then things go horribly wrong. Before we ever get to the dinner itself, Brochant invites Pignon to drinks at his apartment à deux - his wife having absented herself in disgust - and his poor Pignon, through sheer clumsiness, succeeds in setting in motion a chain of events which destroys Brochant's marriage, and his life.

Le Dîner de Cons is an elegantly contructed chamber piece, a bizarre and unsettling farce; it candidly shows its stage origins, and yet it never seems static or claustrophobic and is tightly managed at a spare running time of 80 minutes.

It is a broad yet astute comedy of manners which emerges as a monstrous hybrid of Buñuel and Feydeau, with a generous dollop of Laurel and Hardy. Jacques Villeret and Thierry Lhermitte play their roles expertly as the ill-matched couple who drag each other down into a strange little comic hell of despair.

And what is very impressive is the way the picture steers terrifyingly close to a sentimental ending: Pignon exacts a revenge of neat poetic justice on his tormentor, and the film invites us to feel sorry for the poor chump, his sad life and his matchstick models. Then, with one glorious and sickening wrench, which I will not disclose, Veber turns the action around in an absurd twist which plunges them both into an inglorious and dishonourable dungheap of con-dom.

Hours after the film ended, I found myself giggling at it. With pitiless deadpan severity, this movie shrugs off any suggestion of a humane or optimistic gloss on their dire lives, and succeeds in making it funny. What can I say? It is a little classic.