If it ain’t broke, milk it, as they say in Hollywood.

So why did New Jersey homeboy Kevin Smith wait all of 12 years before returning to the successful small-town-buddies formula of his cult debut, Clerks?

True, Smith has done strident variations on the theme – Mallrats – and lame spin-offs – Jay and Silent Bob Strike Back(JSBSB).

But this is the first time that he’s summoned his high-school friends Brian O’Halloran and Jeff Anderson back for a rematch as eternal clerks Dante Hicks and Randal Graves.

The result sometimes feels like an extended sitcom episode – but it’s a funny, fast-paced, risque sitcom with some great one-liners.

Unprudish slacker and post-slacker audiences will lap this up, though only die hard Smith fans will buy the (thankfully brief) doses of sentimental you’re-my-buddy schmaltz.

A surprise R rating (Smith was apparently braced for another NC-17 repeal battle) will help Clerks II to equal and perhaps top the $30m domestic takings of the director’s top grossers, JSBSB and Dogma; and auxiliary sales should be buoyant.

Smith’s films generally do only modestly in non-English-speaking territories overseas, if they get seen at all.

But Clerks II has enough standalone panache to overcome the lack of a serious fan base abroad and achieve at least comic curio status.

The opening scene switches neatly between black and white – a nostalgic homage to the original Clerks – and colour, as an older, paunchier Dante turns up for another day at the Quick Stop grocery store, only to discover that [SPOILER].

Responsible Dante and his sardonic, foul-mouthed, live-by-the-day buddy Randall are forced to take jobs at Mooby’s, a fast-food chain based on a golden calf character that is one of the recurring motifs in Smith’s comic Sim City (a world known as the Viewaskewniverse, after his View Askew production company).

Dante now has a [SPOILERS].

Outside the store, stoner drug dealers Jay (Jason Mewes) and Silent Bob (Smith himself), lounge around once more, unchanged after rehab except for [SPOILER].

In fan-service comedy franchises like this, just being seen is half the battle: hence the cameos by Smith regulars Ben Affleck and Jason Lee.

So much for the plot. The core business of this film (which was originally to have been called The Passion Of The Clerks) is to keep the laughs coming, and the badinage here is as good as anything Smith has written.

PC orthodoxies are sniped at in the extended [SPOILER] gags, there’s a running series of [SPOILER], and the gross-out sexual skits include [SPOILER] out-porks Porky’s.

But however smutty it gets, the humour is grounded in character and the dead-end tedium of small town America and its McJobs.

The look of the thing is televisual, and so is much of the acting; only a sensuous, screen-hogging Dawson drags the standard up a notch or two. Whatever: Clerks II is funny, and it moves along at a cracking pace. Which is more than you can say for most of the films Smith has made since the original Clerks.