Stephen and the Sexy Partridge, Trafalgar Studios 2, London

(Pete Le May)

Are you game?" the sexy partridge asks Stephen. "I am!" If such chirpy wit were characteristic of Lily Bevan and Finnian O'Neill's ten o'clock Christmas show, one would leave the theatre singing "fa la la la la". But when Stephen later asks his friend, doubting her sobriety, "Are you high?", one can't help thinking that the adjective could refer to the age and odour of many of her jokes.

Stephen (O'Neill) is in disgrace with his girlfriend for atrocious behaviour at her office party: he drank too much, fought, and rudely refused an unusual dish on the Christmas buffet, saying he didn't want to taste "Matt's balls". Trying to make amends, he shops aimlessly until rescued by Bevan, a magic partridge in Victorian underwear, who takes him on a journey of self-knowledge and redemption in the form of a musical parody of "The Twelve Days of Christmas".

Cal McCrystal's production might be more enjoyable if O'Neill, instead of emphasising Stephen's coarseness and stupidity, took them for granted and stressed his innocence. But the authors' reimaginings of the strange yuletide gifts, illustrated by six very game girls, include several satisfying gags. Some of the ten lords-a-leaping are Frodo, Archer, Flatley (of the Dance), and Vader, the last resembling a disoriented orang-utan who has got tangled in a nun's habit. "Five gold rings" is a quiz show presided over by a vicious Anne Robinson who Tasers the cackling goose contestants with her microphone.

Most of the humour, though, is limply instead of gloriously silly, lazy and smug. The authors think we will be amused by some short and all-too-common words, by Bevan's singing "I am the partridge – koo koo kachoo!", by a reference to ancient TV (Mork and Mindy) or to what's going on in the theatre's main house. "Lenny Henry's busy killing his wife!" "Dawn French?" "No, Desdemona!" When the "nine ladies dancing" show up in saris and pull Stephen into a Bollywood number, the choppy, inane rhythm seems made for a satirical patter song – who could resist the rhyme of "Diwali" and "doolally"?

But there are no lyrics, just a lot of grinning and whirling. On the whole, I'd have had a better time with Alan Partridge. Or Eric.

To 2 January (0844 871 7615)