'Forgetting Sarah Marshall': Typically funny Apatow

We know at least one thing about the Judd Apatow comedy formula - he's not trying to seduce you with the hypnotic good looks of his leading men.

Steve Carell, Michael Cera, Jonah Hill, Seth Rogen, John C. Reilly - none looms as a threat to displace Brad Pitt as the world's sexiest man.

Nothing in Apatow's schlub's gallery of male leads, however, prepares you for the breathtaking regularness of the guy in "Forgetting Sarah Marshall."

Jason Segel is hulking, stooped, doughy and without a single developed muscle or perceptible sinew. He is also, as you've probably heard, stark naked in one of his key scenes. For several minutes. Fully, frontally naked.

He performs his extended nude scene at the movie's outset - his foxy girlfriend (Kristen Bell) is dumping him, and he decides that putting on his clothes will somehow make the break-up final and official.

That's a funny idea, but the unhinged laughter emanating from the audience derives in part from the audacity/incongruity of the lumpen Segel and his not-ready-for-prime-time physique.

It was during the '90s that the transgressive comedy ran out of things to transgress, but Apatow may be onto something new here. What makes Segel's nakedness daring isn't the package, but the shabby wrapping that surrounds it.

In this age of the airbrush, of botox, steroids, HGH, personal Nazi trainers and the rampant emaciation among movie stars that advertises sit-ups and self-denial - Segel's physique is a form of rebellion.

It's also very much in keeping with his character, Peter (an apt first name) Bretter. While Sarah is away filming her TV show (seen in hilarious outtakes, it's a "CSI"-ish show with William Baldwin making mock ghoulish remarks about corpses), Peter is on the couch, procrastinating (he's a composer), eating mountains of Fruit Loops out of a wok.

He has the body that prolonged inertia can create, and it's really the inertia that sends his girlfriend packing. When she leaves, the inconsolable Peter impulsively decides to go somewhere warm for some tropical healing.

He chooses Hawaii and - small, cruel world - ends up staying in the same hotel as his ex (a coincidence the movie manages to explain) and her priapic, Euro-pop-star boyfriend (the movie is sexually candid, frequently side-splitting).

The plot finds the lovelorn Peter getting sympathy from the hotel's foxy hostess (Mila Kunis) - herself still smarting from a breakup - a pairing that sets in motion the movie's love-triangle.

Mostly though, "Marshall" is a typical Apatow comedy (he produces, Nicholas Stoller directs), meaning that it pays scant attention to conventional narrative. It strings together loosely related (often improvised) scenes and gags (with regulars Paul Rudd and Hill, who understand the system and make use of their freedom to riff). The Apatow army encourages innovation, shoots long scenes and selects the good stuff in the editing booth - it's why his movies are consistent laugh-getters, even if they lack classic structure.

"Marshall" has the usual Apatow quotient of laughs, and that's no small achievement. "Marshall," though, cares even less than other Apatow movies for the building blocks of story and character.

And Segel, though he wrote the script and knows where the jokes are, sometimes does not appear to be what you would formally call . . . um, an actor. Authentic emotions just don't register in his big, blank face.

But we're not here for "Masterpiece Theater. "

We're here for laughs.

And Apatow, as usual, gives us what we want. *

Produced by Judd Apatow and Shauna Robertson, directed by Nicholas Stoller, written by Jason Segel, music by Lyle Workman, distributed by Universal Pictures.