By Neil White

GROSS, bawdy and swear-word-littered it may be but Hangover is the stand-out comedy of the year so far.

The background story is well-trodden with four very different characters taking a road trip to Las Vegas for a bachelor party.

But that is where the Hollywood clichés end and a highly imaginative script takes over.

The quartet book into a room at Caesar's Palace, make a toast on its roof and the next thing they know is when three of them wake up in their trashed room the next morning with a tiger in the bathroom, a baby in the closet, the groom disappeared and one of them having been married in the middle of the night.

Thereafter, their attempt to retrace their steps and find their missing man in time for his wedding prove hilarious, both in what they do and the discovery of what they have done.

The four friends are made up of a good-looking fed-up-with-his life teacher Phil (Bradley Cooper), henpecked dentist Stu (Ed Helms), the groom Doug (Justin Bartha) and his potential brother-in-law Alan (Zach Galifianakis).

The gags are spread around liberally but are particularly effective in the hands of Galifianakis, who reminds a little of Trigger from Only Fools And Horses, with his random comments.

The physical jokes work best, however, with the baby (which happens to be Heather Graham's) and the tiger (which is Mike Tyson's!) at the centre of much of the fun.

Scenes involving the police taking retribution for a squad car being stolen and a gangster gaining revenge for being locked up naked in a boot, are equally memorable.

It is a wacky plot which in the wrong hands could have easily been adopted as yet another Seth Rogen movie.

Yet, despite these characters being offbeat and there being many references to drugs and drink, they don't bathe in a couldn't-care-less attitude in the way the cast does in Knocked Up or Pineapple Express.

Their remorse for their actions actually makes them more appealing as does the comeuppances they receive.

Cracking cameos from Graham, as the hooker with a heart, and Ken Yeoung as the naked gangster add to the merriment.

Ironically, Galifianakis (What Happens In Vegas), Cooper (He's Just Not That Into You) and Helms (Meet Dave) have all appeared in the sort of cheesy comedies which give Hollywood a bad name.

Here they prove what they can do with a cracking script.

It is hard to believe that writers Scott Moore and Jon Lucas were responsible for the recent lame duck Ghosts of Girlfriends Past. Here, with director Todd Phillips, they have created chemistry.

And with Hangover 2 already being planned, let's hope they have a formula which they can repeat.