‘Ali G’ acts out in a narrow niche

British comedian Sacha Baron Cohen begins the second and quite possibly last American season of his “Da Ali G Show� Sunday night on HBO. Two seasons was all he managed in the UK, where his breakout fame quickly made it impossible for him to practice his stock-in-trade -- the guerrilla spoof interview, in which respectable, even respected, individuals are lured into patience-trying, sometimes revealing, exchanges with one of Cohen’s three characters.

They are the namesake “hip-hop journalist� Ali G, a gangsta wannabe of confusing ethnic provenance; Borat Sagdiyev, a roving correspondent from Kazakhstan; and Bruno, a flamboyantly gay Austrian fashion and lifestyle reporter.

The practical joke has a long if not exactly honorable history in the broadcast media, going back to “Truth or Consequences� and “This Is Your Life,� through “Candid Camera� to “Punk’d,� though Baron Cohen’s closest antecedent is Chris Morris’ more subversive “Brass Eye,� another British series in which well-known figures were similarly duped. But where Morris’ tack was to seem better informed than the people he “interviewed� in order to smoothly sway them to his nonsense, Baron Cohen’s characters play the fool.

This just makes his “victims� look patient or indulgent or kind. ABC newsman Sam Donaldson, the new season’s first guest, seems to regard Ali as a half-wit, but is too polite to say so, and even consents to say, “Mad props to the hood, yo.� This is cute, but not cutting.

Though Baron Cohen is clever and amusing and quick on his feet, his humor boils down to a few endlessly repeated gambits: malapropisms, misunderstandings, and outrageousness in the guise of innocence.

Ali G confuses Watergate with “Waterworld,� the shootings of JFK and JR (both were in Dallas, after all), and Homer and O.J. Simpson. He says “incense� for “incest� and when he’s corrected substitutes “insects.�

As Bruno, Baron Cohen asks a gay-converting minister, “So why is being gay so out this season?� and professes shock at the minister’s claim to be straight. “So if I were to give you a lap dance right here and now, you’re telling me you wouldn’t be turned on?�

The show depends on the fact that there is so much television now, so many niche networks and public-access avenues, a person might find himself being interviewed by anyone. It’s necessary, of course, that the subjects be a little out of touch -- provincial enough that, the question of being familiar with “Da Ali G Show� aside, they can’t recognize Baron Cohen’s characters for the outlandish parodies they are. (Peter Jennings possibly would have smelled a rat, where Donaldson could not.) And so they tend to be old and/or conservative, and often semi-retired -- “former� officials, with enough time on their hands to sit down with an unintelligible idiot in a big yellow track suit.

Still, the heart of the show is Baron Cohen himself, the man behind the masks, and just how far he will go and what he will get away with. It’s not that different from “Jackass,� really. In one sequence, as Borat, he shows pornographic pictures of himself with his “sister� to a couple of old Southerner gentlemen he has come to interview about their wine-tasting club. “We make a joke! We pretend to be husband and wife.� We also see him downing glass after glass of wine, and quite obviously making himself actually drunk. “My mother, she never loved me,� he sobs. “She tell me sometimes she wish she was rape by someone else, that I was never born.� He asks for a hug. The gentlemen treat him kindly.

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‘Da Ali G Show’

Where: HBO

When: Premieres 10:30 p.m. Sunday

Rating: The network has rated the series TV-MA (may not be suitable for children under the age of 17).

Sacha Baron Cohen...Ali G., Borat Sagdiyev, Bruno

Creator, Sacha Baron Cohen. Executive producers, Sacha Baron Cohen, Dan Mazer and Peter Fincham. Director, James Bobin. Writers, Sacha Baron Cohen, Ant Hines, Dan Mazer, James Bobin, Jamie Glasman, Jeff Stilson, Richard Dahm and Seth Rogen & Evan Goldberg.