Warning: Avenue Q is not – repeat not – Sesame Street. At the very nearest (I’m guessing here) it is what might happen to Sesame Street if the producers of Jerry Springer: the Opera got wired one night and said: “Have you ever thought about Bert and Ernie naked?”

Ribald throughout – for your pleasure – Avenue Q nonetheless has a much gentler finish than, say, Team America (though, for context, creators Robert Lopez and Jeff Marx are currently working on a musical with Trey Parker and Matt Stone, the vulgarian South Park geniuses – shotgun reviewing that!). This is partly because its renegade progenitors are hell-bent on making musicals ‘accessible’ to the very people – me, for instance – who’d rather be hit in the face with an axe than sit through My Fair Lady. But it’s also because Avenue Q is predicated on the idea of asking genuine questions about the predicaments of adult life. And so it manages to mercilessly take the rise out of musical theatre, while simultaneously restoring my faith in the West End. Score!

The eponymous avenue is inhabited exclusively by unemployed, 30-something arts types, all living there because it’s a cheaper neighbourhood than Avenues A-P. A (rightly) failed comedian; a perma-temping literature graduate; a dappy kindergarten assistant; a psychiatrist with all the soothing reassurance of Kim Jong Il; a self-loathing ex-teen-celebrity janitor. Oh, and flatmates Bert and Ernie (sorry – Rod and Nicky. Some names have been changed to avoid lawsuits). Rod is a gay Republican and Nicky hasn’t twigged. As if! I mean, the haircut and the suit alone positively scream Republican.

Backed by some brilliantly inventive stagecraft, and often playing human roles as well as puppeteering, Julie Atherton (as Kate Monster and Lucy the Slut) and Daniel Boys (as Princeton (BA Hons.) and Rod) lead a new cast through two hours of astonishingly versatile performances – the things these guys can depict, and with one hand up a puppet’s shirt, too! – while belting out such classic hits as “It sucks to be me”, “If you were gay” (no connection), “You Can Be as Loud as the Hell You Want (When You're Making Love)” and – for intellectual balance – “Everyone’s a Little Bit Racist”.

Or lacist, of course, if you’re Oriental. Every conceivable stereotype is covered, and with a big grin, too: “Ethnic jokes might be uncouth / but you laugh because they’re based on truth.” This is next-generation Tom Lehrer: not one lyrical mis-step in the entire show.

They also make great play with the time-honoured educational videos, sending up the hopelessly earnest didacticism of Sesame Street while tackling perennial conundrums like “How to propose”. (I’m willing to bet this is also the only recorded instance of the word ‘schadenfreude’ in a musical.) By my reckoning the entire house was in stitches every 15 seconds – more, if you average the frequent three-minute barrages. So, if someone you know needs a good laugh this new year, here’s your fix. But get booking; it closes in three months.

n Until March 28, tickets: £10-£51.50. 0844 482 5138 www.avenueqthemusical.co.uk