Inside the auditorium, though, it's a different matter. Hilarity is unconfined right from the opening penis joke, and Rik Mayall's use of the phrase "Wanker's whiplash" even elicits a spontaneous round of applause. When it first soiled the nation's television screens, Bottom had the look of a cosy retirement pasture for Rik Mayall and Ade Edmondson's Young Ones characters, but it seems to have touched a nerve in the rat-ridden sewer of the British unconscious. Twice as many people watched the last series as watched The Day Today in a similar slot, and they weren't only drunken 12-year-olds staggering out of the pub to be home by nine. Comedy luminaries of the calibre of Vic Reeves & Bob Mortimer and the writers of Father Ted are happy to speak highly of it.
And yet, puerile, childish and obsessed with bodily functions as it is, there is something strangely not funny about the live Bottom experience. The explosions are excellent, the sadism is neatly choreographed, and the set of this two-hour stage show reproduces the squalor of the television tableau in meticulous detail. But the sense of enclosure and degradation you get out of the little box in the corner of the room just does not come across in a theatre. There is no getting away from the fact that Mayall and Edmondson have civilised hotel rooms to go home to afterwards.
If the essence of comedy is - as inveterate Viz-reader Sigmund Freud suggested - "the awakening of the infantile", then Bottom might seem to have it taped, but there is something depressingly grown-up and routine about the sheer scale of this tour. Mayall and Edmondson are going to be repeating the line "Hobnob?" "No I've got an ordinary one" to a different packed house every night until Christmas. It is quite possible that towards the end of the run their performances will be sounding a genuinely psychotic note.
At the moment there are just a couple of moments of authentic tastelessness - most notably when Edmondson describes an exploding bathroom-hygiene product as being "from the ethnic end of the cleansing spectrum" - and things liven up a bit in the second half when Mayall starts to forget his lines and his partner threatens to "do a Stephen Fry" on him. But by the end of the prison scene, you know how Rik Mayall is supposed to feel when he says, "I wish I hadn't eaten the contents of the slop bucket".
The Right Size's Stop Calling Me Vernon has taken a year to get down to London after a much lauded debut at Edinburgh in 1994, but has lost none of its freshness. Hamish McColl and Sean Foley's beautifully designed and impeccably performed show turns the spotlight on a hard-pressed vaudeville double act and doubles Bottom's gag-count in half the time-span. The slapstick violence has an impressively authentic feel to it too: by the end of the night the stage is awash with blood, sweat and custard.
'Bottom': Bournemouth Int'l Centre (01202 297297), tonight; Portsmouth Guildhall (01705 824355), Mon; then touring to 20 Dec. 'Stop Calling Me Vernon': Lyric, W6 (0181 741 2311), to 14 Oct.