An age-restricted teaser trailer for Ben Stiller’s new action-comedy Tropic Thunder is now online at the film’s official site.

We first talked about the film the other day and showed a photo from movie of Stiller, Jack Black, and an interesting-looking Robert Downey, Jr (see First Look: ‘Tropic Thunder’). The trio play a group of high-maintenance A-list actors making a big-budget Vietnam War movie. When the filmmakers get fed up with the actors, they send them out into the jungle for real, but the actors don’t know they’re in real danger! Downey plays an Oscar-winning actor who’s so dedicated to the role, which was originally written for a black actor, that he dyes his skin.

The age-restricted teaser is presented as a teaser for the Vietnam War movie the characters are filming, set against the sounds of Creedence Clearwater Revival’s “Fortunate Son” — because you can’t tease a Vietnam War movie without CCR’s anti-Vietnam War anthem and these guys know it!

Tropic Thunder hits theaters on August 15, 2008.