Sent into the jungles of Southeast Asia to find some motivation, they become unintentionally entangled in real-life peril at the hands of drug lords. Stiller is Tugg Speedman, a fading action star who has signed on to "the most expensive war movie ever made" in an effort to save his flagging career. Kirk Lazarus (Robert Downey Jr.) is a five-time Academy Award-winning Australian so into "method acting" that he has surgically darkened his skin to play a black man.

Joining them on the Vietnam epic is Jeff Portnoy (Jack Black), a coked-up comedian known best for gross-out films and fart jokes; dewy-eyed newcomer Kevin Sandusky (stringy Jay Baruchel); and looking to go legit with "Tropic Thunder" is Alpa Chino (Brandon T. Jackson), a gangster rapper who manages to plug his energy drink in the 1960s-set film.

Of course, nothing goes according to plan. While Tugg's mollifying agent (Matthew McConaughey) grows increasingly anxious, things turn deadly as drug dealers violently ambush the cast and crew, kill some, kidnap others and leave those left standing armed only with their acting as ammo to get out alive.

Funny stuff, as is Tom Cruise's extended (and almost unrecognizable) cameo as megalomaniac studio head Les Grossman. It takes a moment to sink in that it’s Cruise under the flab, hairpiece and sweaty misanthropy.