Ben Stiller seems to know this, and in his latest satirical movie “Tropic Thunder,” which was just released on DVD, the prickly comedian takes aim at movies like “Apocalypse Now” and “Platoon” and blows his target to smithereens.

Kicking off with a quick series of fake movie trailers, he gives us a taste of the actors of this film-within-a-film. There's Jack Black as an obnoxious party animal who cranks out flatulent gross-out comedies not unlike Eddie Murphy's family of fatties, the Krumps. Robert Downey, Jr. plays an Australian actor, not to be confused with Russell Crowe, who's just starred in a film about forbidden love in a monastery. He takes himself and his projects so seriously that he's undergone a surgical procedure to actually have his skin pigment darkened to play an African-American soldier. Then there's Stiller himself, as the airhead macho man who channels Tom Cruise and who plays a mentally-challenged farm hand because he thinks it will win him an Oscar.

As “Tropic Thunder” begins, all of these Hollywood types are gathered in Southeast Asia to make a hugely expensive war film. But as the flick runs behind schedule and the stars' egos threaten to take over the production, the director decides to ditch the script and throw them into the jungle to really live the film.

Needless to say, things don't go as planned. There's a real band of drug smugglers with real guns firing real bullets at them, and the pampered Hollywood crybabies have no idea it isn't fake.

Stiller and Black are great, as are the other grunts who round out the platoon, but it's Downey, lost behind his Method acting and new skin color, who steals the film. Only an actor as crazy and fearless as him could get away with putting on blackface in 2008. Every time he shows up onscreen, you'll want to rewind the scene and watch it all over again.

Now for a look at what else is new on DVD: in “Wall-E,” an animated trash compactor looks for love on what's left of Earth; in “Gonzo,” a documentary explores the life and high times of Hunter Thompson; and in “Hawaii Five-O,” the first five seasons of the '70s cop show get a boxed set.