You see, “Tropic Thunder” exposes the belief among many people in the movie business that the surest way to get nominated for an Academy Award is to play a character with mental challenges. Dustin Hoffman in “Rain Man,” Tom Hanks in “Forrest Gump,” and Russell Crowe in “A Beautiful Mind” are exhibit A, B and C when it comes to proof. That may not seem like a very big deal, but it's a running gag throughout “Tropic Thunder” and prompts exchanges like this one between Tugg Speedman (Stiller) and Kirk Lazarus (Robert Downey Jr.):

Speedman: There were times while I was playing Jack where I felt … retarded. Like really retarded.

Lazarus: Moronical?

Speedman: Yeah.

Lazarus: An imbecile?

Speedman: Yeah.

What's funny about that? Well, for one thing, Lazarus is a tough-talking, cigar-chomping cheerleader of a soldier who happens to be black. Robert Downey Jr. gives a brilliant performance in blackface. That's right, a white actor playing a black character. Or, as Lazarus says, "I'm just a dude playing a dude pretending to be another dude."

Lazarus, an Australian who has won four Oscars, speaks with some clout when he says Speedman blew his Oscar shot by playing a "full retard" in a move called “Simple Jack” when what was called for was a more subtle disability.

Speedman is an action movie star whose firepower is fading. He's recycled one character through four sequels, has played that retarded rube in an Oscar-bid-of-a-movie called “Simple Jack,” and is now leading a band of brothers in a Vietnam epic. But things aren't going well on the set, and what's worse is that the studio head (Tom Cruise) hates the footage he's seeing. It's decided that it needs more reality. So Speedman, along with a squad that includes Lazarus and Jeff Portnoy (Jack Black), gets choppered deep into the jungle and lands right in the middle of a massive drug operation protected by a well-armed militia. This is no movie; this is war!

In a movie like “Tropic Thunder,” it helps if you get some of the references to current movie business practices. And many of you will. Some of today's young stars have no problem with gnawing on the hand that feeds them. Movies are a business. As long as we keep paying to laugh at the latest in-jokes, the studios will take the abuse to the bank.

Once you get past the "retard" controversy, the riffing on war movie clichés, and the plethora of inside show business jokes, you'll find that “Tropic Thunder” is a lot of fun for one movie. The plot never gets in the way of that fun because getting bogged down is not what this is about. If Stiller's got a style, it is to mimic the startling spontaneity of combat. He keeps things clipping along by putting his actors to great use. Downey Jr. as Lazarus commands the screen the way Samuel Jackson can when he's in a take-charge, kick ass frame of mind. (In fact, I'd love to see Downey Jr. as a black character appearing alongside Jackson in some future project. I'm sure Downey Jr. could more than hold his own.) Steve Coogan plays Damien, the director who's British and pretty clueless. This guy's a British comic who brings a nice diversity to the very American band of brothers. Nick Nolte plays the weary, seasoned Vietnam vet brought in as a consultant because he was there — and he'll never be the same again. Cruise is a kick as the nutso studio boss whose moves are choreographed like a ballet of abuse toward the many who work for him. Matthew McConaughey plays the smarmy agent who will tell his client (Speedman) anything he wants to hear. With a cast like that, success is not guaranteed, but there's sure to be some fun. Everyone's firing off lines throughout, so it hardly matters how the movie crew manages to defeat the drug troops.

Have you ever spotted an actor in a movie and just kind of recognized him or her but couldn't put a name to the face? You know you've seen the actor somewhere else, but you can't nail down where. Such was the case in “Tropic Thunder” with one of the soldiers. He's a tall, skinny kid whose has not got good looks but is a presence nonetheless. I had to look him up. He's Jay Baruchel, and he played Danger Barch in Clint Eastwood's wonderful film “Million Dollar Baby.” Danger was the kid in the gym who wore long johns to work out and whose self opinion far exceeded his skills in the ring. I knew there was a reason I remembered him.

“Tropic Thunder” isn't a great movie. It’s more of a series of satirical character sketches performed by some very funny men. (I can't recall a female character of any significance in “Tropic Thunder.” But is there ever a woman who matters in a real war movie?) It easily falls into the sub-genre of gross-out movies with some action and dialogue that's raunchy enough to shock us in ways we still haven't been shocked. I guess movies stop being fun when we're not even a little shocked at what they'll say and do.

Written by Bill Gallagher - the news director of KPAM 860.