From Dumber & Dumber to Dodgeball, Caucasian males have dominated the frat-boy comedy with a smattering of other races normally shoed in for comic effect.

This second outing from Dude, Where's My Car? director Danny Leiner bucks that trend by casting two Americans of Asian and Korean origin in the lead roles.

John Cho - a veteran of the American Pie series - is Harold Lee, an office drone witheringly referred to as a Twinkie - yellow on the outside, white on the inside.

His pal and flatmate is Kumar Patel (Penn), a party animal half-heartedly trying to get into medical school to keep his aspirational Asian doctor dad happy.

What they have in common is an unfettered enthusiasm for industrial strength weed and the ability to devote their spare time to doing absolutely nothing.

One night, after a particularly heavy session on the funny fags, they get the munchies and decide only a burger from White Castle will sate their appetite.

What follows is a routine road movie with the hapless duo running into rednecks, creepy truckers with suppurating boils and pliant wives as well as bent coppers.

But what makes it different is the fresh slant brought to familiar fare by their racial characteristics with most of the jokes at the expense of themselves.

OK, so there's the customary toilet/diarrhoea scene (which appears almost a contractual obligation in these sorts of movies) but this is a far smarter movie than that.

One beautifully played scene has them desperately fighting the urge to holler along to Total Eclipse of the Heart after discovering their redneck foes have a weakness for camp standards.

Another sees them trapped in a seduction scene between a Bible-thumping, pustule-riddled backwoodsman and his inexplicably pretty young wife.

On the downside, British audiences may miss out on the reference to popular American series Doogie Howser MD while one Holocaust gag is difficult to justify.

Nevertheless, Penn and Cho are extremely likeable leads well served with a taut, witty script and an incident-strewn plot confident to take the odd surreal turn.

Perhaps best of all, it's got absolutely nothing to do with the Kumars at No 42.

Tim Evans