TROPIC THUNDER — ** — Ben Stiller, Robert Downey Jr., Jack Black; rated R (violence, vulgarity, profanity, gore, drugs, slurs, torture, nude art); Carmike 12 and Ritz; Century Sandy and South Salt Lake; Cinemark Jordan Landing; Megaplex District, Gateway and Jordan Commons

"Tropic Thunder" is nearly a disaster movie of a different sort, a big-budgeted bust that could prove to be an embarrassment to at least a few of the bigger-name actors in its cast.

And no, that's not in reference to the film-within-a-film that's featured in this hackneyed show-business spoof, even though it also goes by that same name.

What's so odd is this rather toothless comedy tries to parody bad (or at least cliched) Hollywood filmmaking, but is equally guilty of the same thing. Also, there's a certain amount of smugness to the material that is extremely off-putting.

Ben Stiller co-wrote the script, directed and plays Tugg Speedman, a once-popular action film star whose best days may be behind him.

Still, he's hoping for a big comeback — in, of all places, Vietnam, where he's supposed to star in a war movie. Tugg's co-stars include Kirk Lazarus (Robert Downey Jr.), an Oscar-winning Aussie who's recently had cosmetic surgery to improve his "craft," and Jeff Portnoy (Jack Black), a drug-addicted funnyman.

But their director, Damien Cockburn (Steve Coogan), is quickly growing tired of these pampered superstars. So he plants them in the middle of the Vietnamese jungle, not realizing the area has been overrun by violent, Southeast Asian drug runners.

This set-up isn't horrible. But Stiller and company repeat the same five jokes so many times that they're not only unfunny, they become painfully unfunny.

That's especially true of subplots that involve Black's character (which include a few direct jabs at Eddie Murphy) and a greedy studio executive played by a nearly unrecognizable Tom Cruise.

And the Stiller character's descent into madness — "Apocalyse Now," anyone? — goes on too long and is annoying.

To be fair, Downey impresses as a white actor pretending to be an African-American character, and Jay Baruchel is good as an inexperienced, impressionable actor.

"Tropic Thunder" is rated R for strong scenes of violent action (warfare, including gunplay and shootings, beatings, explosive and vehicular mayhem, and violence against children), vulgar sexual and scatological humor (several flatulence gags), strong sexual language (profanity and vulgar references), some surprisingly graphic blood and gore, drug content (narcotics use and references), racial epithets, and other derogatory slurs and language, a brief torture scene (done for laughs), and glimpses of nude art. Running time: 107 minutes.

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