At some time in the career of every screen comedian, there comes a point where he has to make peace with The Character. Adam Sandler is The Man-Child Knucklehead. Vince Vaughn is The Tightly-Wound Motor-Mouth. Jack Black is The Wild-Eyed Wannabe Rocker. If you last long enough, maybe you get to re-invent yourself—like Steve Martin as 60-something father figure, though he has returned to pratfalls—but even then it doesn't always work. Dramatic actors may get to be chameleons, but when it comes to our cinematic clowns, we like to know who they are, and it has always been so. Charlie Chaplin and Groucho Marx didn't become icons because they wanted to "stretch" as performers.

Seth Rogen seemed to get this concept early on. From his breakout roles for Judd Apatow in The 40 Year Old Virgin and Knocked Up to last year's Pineapple Express, Rogen embraced the role of the potty-mouthed but ultimately genial slacker. This was his milieu, and he excelled in it. So why now do we find him in something as wrong for him as Observe and Report?

His character here is Ronnie Barnhardt, "head of security" for the suburban Forest Ridge shopping mall. And Ronnie is one weird dude. His interest in Brandi (Anna Faris), the bubble-headed cosmetics counter girl, crosses the line into stalking. His method of investigating crimes—like a spree by a good old-fashioned trenchcoat-wearing flasher, or after-hours robberies—tends to completely alienate local police detective Harrison (Ray Liotta). Interviewing potential "suspects" generally takes the form of aggressively racist profiling of whomever happens to have brown skin. He suffers from delusions of grandeur, despite living with his alcoholic mom (Celia Weston). This, by the way, is our hero.

He also has dreams of being an actual police officer, and this is where writer/director Jody Hill (The Foot Fist Way, HBO's Eastbound & Down) loses any sense of who Ronnie is. When Ronnie goes on a "ride-along" with a pissed-off Harrison, he gets dumped in a horrible part of town and surrounded by crack dealers. So naturally, Ronnie turns into a baton-wielding badass, dispatching his adversaries with a crunch of teeth and snapping bones. Observe and Report, rather than attempting to be a coherent movie, simply becomes a collection of whatever notions Hill seems to find funny at the moment—whether it's silly lisping voices, a drunken almost-date-rape, or a five-minute foot-chase involving full-frontal male nudity.

And the fact is, some of Hill's random stuff is funny at the moment. There's a showdown between Ronnie and one of his various ethnic adversaries (Aziz Ansari) that becomes the most drawn-out exchange of "f—k you's" you've ever seen. A drug-fueled montage includes an all-out assault by Ronnie and his partner (Michael Peña) on a group of skateboarders. There's a deliriously overwrought monologue by Ronnie in which he envisions himself a Batman-style vigilante. And simply casting Faris (typically hilarious), Danny McBride (as the boss crackhead) and Patton Oswalt (as an obnoxious manager of a Cinn-a-Bon-type establishment) guarantees a few chuckles.

But at the center is Rogen, and the center doesn't hold. It would have been pretty difficult for anyone to make sense of the scattershot way in which Hill has created Ronnie, and it's probably testimony to Rogen's fundamental likeability that the audience is with him even when Ronnie's cold-cocking innocent people. What the character would have required, though, to have any chance at succeeding, is an element of aggressive unpredictability. Rogen can't pull off the wild-eyed threat of someone too unstable to be given any kind of authority. Even sporting a buzz-cut, he looks more like the kind of guy you'd like to hang out with on the couch eating pizza. Jack Black maybe pulls this off. Rogen, not even close.

I'm not convinced general audiences would have embraced Observe and Report's brand of anti-social humor in any case—Apatow manages to be much more humanistic in his sophomoric shenanigans—but they'll forgive a lot if they can embrace a star in the kind of part that feels comfortable and familiar. Call it typecasting, call it unfair, but we know who our favorite funny guys really are—even when they don't.

OBSERVE AND REPORT

** (two out of four stars)

Starring: Seth Rogen, Anna Faris, Ray Liotta.

Written and directed by Jody Hill

Rated R.