Star rating: **** Dir: Greg Mottola With: Jonah Hill, Michael Cera, Christopher Mintz-Plasse, Seth Rogen

Watch the trailer here Is releasing the spectacularly vulgar Superbad so soon after the equally bawdy Knocked Up a stroke of marketing genius or an almighty blunder? Given the takings for KU, probably the former. Not that everyone feels that the likes of Seth Rogen (who co-wrote and appears in Superbad), Judd Apatow (KU writer-director and Superbad producer) and Jonah Hill (star of Superbad), should be encouraged. A backlash is stirring against the maestros of gross-out comedy and their brand of sex-obsessed slob operas. Taking umbrage on behalf of women everywhere, one (male) film writer declared: "The dark ages are back."

Now, this critic bows to no-one in her ability to purse lips, raise an eyebrow and sigh mightily when confronted with crudity. After Eddie Murphy's Norbit, it was a tie between myself and a certain Spice Girl as to who would most like to subject the fatsuit-wearing clot to cruel and unusual punishment (watching Spiceworld: The Movie in perpetuity, perhaps). There's just one problem with having a sense of humour failure over Greg Mottola's coming of age tale: the film is a hoot. More than that, it's unfailingly sweet as well.

As plots go, Superbad's is very simple. This is not the kind of finely spun allegory that Bergman, looking down from heaven, will regard as the one that got away. It's the end of high school and two teenagers, best friends since childhood, are about to go their separate ways to college. There's a party coming up, and our heroes, Seth and Evan (Jonah Hill and Michael Cera) would like to (a) get drunk and (b) get up close and personal with girls.

Seth and Evan have been friends for so long they have ceased, until now, to wonder what it is they see in each other. Both are uber-geeks, ignored or despised by their classmates, but that's where the similarities end. Evan is shy, smart, respectful of women and thin. His buddy is none of the above. Seth has a kind of sexual Tourette's when he's around girls. More so when he's not around them. Bemoaning the fact it has been two years since he was intimate with a female of the species, he's worried that his career as a Lothario may have peaked too early. "You're like Orson Welles," Evan consoles. Seth is a child-man with a plan, however. He's noticed that at parties girls who are drunk as skunks tend to make unfortunate choices of partner. Seth's ambition is to be that unfortunate choice. Knocked Up had the same beauty and the beast, any-slob-can-get-a-gorgeous-woman, premise. It's codswallop, pure make-believe, but let's not be too hard on Mottola and his writers. If every middle-aged male filmmaker were to be locked up for bringing his fantasies to the screen, Hollywood would need jails the size of Texas.

Seth and Evan have secured an invitation to the party on condition they bring booze. That's where their friend Fogell (Christopher Mintz-Plasse) and his fake ID come in. So begins a long night of capers that will involve fights, car accidents, a robbery, a pair of demon policemen (one half of which is Rogen with a handlebar moustache) and a trouser stain the origins of which, even now, are too embarrassing to think about. Let's be very clear: Superbad doesn't just glance at offensiveness, it wanders up, throws an arm around its shoulders, declares "you're my best friend, you are", then vomits down its front.

Although the script crosses the line many times, the gag rate and the performances are such that you can't stay mad at Superbad for long. With each film, Jonah Hill looks more and more like the John Belushi of his generation, Michael Cera is lovably gauche as the gentlemanly Evan, while Christopher Mintz-Plasse comes close to stealing the picture as Fogell the prize klutz. What these characters say and do may be in outrageously bad taste, but there's no obvious malice at work here. These kids are super daft, not super bad or mega nasty, and that made all the difference to this keeper of the pursed lips.

Mintz-Plasse is the one who keeps the movie rolling along when it enters tedious territory. The problems apparent in KU crop up again in Superbad: scenes are allowed to run too long, particularly the cop ones, many lines are just OK rather than great, and the main story gets lost in the fray. There's a danger here for what might be termed, given their obsession with bodily fluids, the splat pack.

Such was the box office success of The 40-Year-Old Virgin and KU that this lot are becoming close to being untouchable. Studios are so busy slapping them on the back no-one is pointing out the flabbiness of the writing and film-making. So long as the laughs keep coming they'll be forgiven. As in KU, Superbad redeems itself in the end through sheer charm. The horrible little bundles of testosterone prove themselves worthy of our affection. They learn that the best of friends will always be there, and girls - shock, horror - are people too. Like the poet never said, if you can keep your head while all around are losing their lunch and blaming it on you, if you can meet with triumph and disaster and wring a laugh from both, then yours is the box office and everything that's in it, and you'll be men my sons.