Tropic Thunder (2008)
Tropic Thunder is a 2008 American action comedy film co-written, co-produced, directed by, and co-starring Ben Stiller. The film also co-stars Robert Downey, Jr. and Jack Black. The main plot revolves around a group of prima donna actors who are making a fictional Vietnam War film. When their frustrated director decides to drop them in the middle of a jungle, they are forced to rely on their acting skills in order to survive the real action and danger. Written by Justin Theroux and Etan Cohen, the film was produced by Red Hour Films and distributed by DreamWorks Pictures through Paramount Pictures.
More at Wikipedia.