Something smells funny - and it's not the Edam

Friends (C4) opened with Carol informing her ex-husband Ross that she's expecting. What gave the scene its edge was that she has recently left him to set up house with a woman. The clueless look on the face of the father-to-be tells you that he's dumbly pondering a biological miracle in which all those X-chromosomes can pool resources and spawn a foetus.

To give the situation an extra spin, the couple are standing inside a prehistoric exhibit at the museum where he's a curator. The mute witnesses to this very modern rite are a pair of neanderthal waxworks. To cap it all, Ross is accident prone, and the arm of one of the dummies has come away in his hands, so when he hugs Carol with his back to camera the rogue limb reappears over his shoulder, as if belonging to his pregnant lesbian ex.

OK, so maybe there's one too many eggs in the omelette, but it serves to show why the American sitcom is so at ease with itself. Friends may take as its starting point the ur-situation - social and sexual tension among disparate types under same roof - but it accords itself the freedom to roam the genres. Over here, where we cleave to pigeonholes, the loose- limb sight gag would never have made it into a dyke-up-the-duff dialogue.

There was another corker of a scene, also involving a fractured relationship, in which Rachel visits Barry in his orthodontic practice to break off their engagement, only he terminates before she can. This time, the witness is not mute, but a kid in the dental chair who gives a terrifically assured cameo as an unwilling, unwitting commentator. Like most American comedies, Friends may have a damp squib for a title, but it's more than worth getting acquainted. It might not be as good as Cheers, but then not every painter worth hanging has to be up there with Vermeer.

Meanwhile, over on the far side, Vic and Bob were back with some thoughts on the necromantic properties of Edam. It can safely be confirmed that this joke has never been cracked before, nor ever will be again. You can't say that about many jokes, including quite a lot of the ones in The Smell of Reeves and Mortimer (BBC2).

As with Cubism, the gifts put on display by television's premier absurdists appear to be within the grasp of anyone. So why aren't we all side-splittingly funny teenage heart-throbs? It requires only a gentle stroll for the imagination to dream up idiocies like, say, a removal van constructed from a cocktail of blancmange and Polyfilla, or a nappy wipe undergoing psychoanalysis - but the mere fact of an implausible conjunction isn't in itself comic. Vic Reeves and Bob Mortimer unburden themselves of their zany worldview (to append to it a glum critical tag) with an almost saintly innocence. If it were ever revealed that either of them conforms to the offstage stereotype of the sad comedian, that would be far more absurd than anything they could come up with themselves. Their genius is their ingenuousness.

As with any comedy out there on the edge, you have to put up with wild inconsistency. The Stars in Their Eyes spoof could have been done by Cannon and Ball, and the thwacking-each-other-with-blunt-instruments sequence has already been seen in Bottom. But the puppet theatre soul singers with unreliable moustaches were a triumph. Best, though, was the advert for the coffee-table volume, Dogs and Their Hats, a not especially funny idea which was about to fall flat when it was revealed that each book contained a complementary copy of Cats in Their Bomber Jackets.

An Open Space Special (BBC2) movingly visited four conscientious objectors, now vigorous old men, who won't be celebrating on Monday. Like most minority movements, especially ones fired by emotion, they had as much clout as straws in the wind. That their views still haven't caught on says less about them than it does about everyone else.