Nude men nude women, grunts, groans, semi-naked wrestling, heavy- handed jokes about pussy, bottoms, more bottoms, still more bottoms: the dedicated voyeur could get his or her thrill from this week's first nights without needing to attend the long-awaited pounds 1m sex musical Voyeurz.

If, instead, you get a kick from the whiff of failure or collect critical flops, this 90-minute show, produced by Michael White (who gave us Oh! Calcutta! and The Rocky Horror Show), and featuring the soft-rock lesbian band Fem 2 Fem, delivers the same sadistic pleasures as the late-lamented Fields of Ambrosia.

Sanity disappears with the last glimpse of the safety curtain, which rises to reveal dancers moving with graceful solemnity in white underpants. The audience has to make a quick interactive choice: laugh at the show or with it.

Let's call it a spoof musical (and laugh with it), a piece of dippy kitsch about a girl from Virginia, Jane (the blonde, mock-virginal Sally Anne Marsh), who goes to New York and discovers sex (or really, the sex industry). The book and lyrics, by Michael Lewis and Peter Rafelson, are as cheerfully and brazenly inane as the thumping bass line. I quote: "How are you doing? What's your name?" "Fine, thanks. I'm Jane." In the background a voice whispers: "Sex on a Train." (This exchange drew a cheer from the noisy first-night audience.)

Voyeurz offers a catch-all mixture of period sex. There's Eighties religious imagery (Madonna cast-offs) with semi-naked dancers thrusting their pelvises at scaffolding. Then there's nostalgic Sixties stuff: sitars, cornflowers, and naked dancers hymning the joys of tantric sex. In terms of outrageousness it doesn't take us much further than the tarts displaying their wares in A Funny Thing Happened on the Way to the Forum (1962). The fetishistic props - the high heels, handcuffs, whips and leather thongs - are as familiar to modern audiences as tennis rackets, cigarette boxes and French windows were to pre-war ones.

From the back of the stalls, with stage smoke, lighting and music, and a dozen dancers wiggling away, this celebration of kinkiness looked about as offensive as a seaside postcard. It would be hard to know what to praise in Voyeurz. But perversely I quite enjoyed it.