And we thought Robert Downey, Jr. in blackface would cause " Tropic Thunder" the most trouble.

Ben Stiller's "Tropic Thunder" is getting heat and faces a mobilized boycott of the film for using "the r-word" to describe the mentally handicapped, report industry trade papers.

In "Simple Jack," a film within the film, Stiller's Hollywood actor character plays a man with intellectual disabilities in a failed attempt at an Oscar bid. The fake poster with a tagline that read, "Once upon a time ... there was a retard" and the website SimpleJackMovie.com were pulled in response to backlash.

"Tropic Thunder's" itself with its references to "Simple Jack," however, remains intact and includes a scene in which Downey Jr. tells Stiller's character, "You went full retard, man. Never go full retard."

Special Olympics and those from other disabled advocacy groups are calling for a boycott of the film and already protested outside the Westwood premiere of the film on Monday night.

DreamWorks spokesman Chip Sullivan says that the studio stands by the film.

"'Tropic Thunder' is an R-rated comedy that satirizes Hollywood and its excesses and makes its point by featuring inappropriate and over-the-top characters in ridiculous situations," he explains. "The film is in no way meant to disparage or harm the image of individuals with disabilities.

"We have had productive discussions with representatives of disability advocacy organizations and look forward to working with them closely in the future," continues Sullivan. "However, no changes or cuts to the film will be made."

"Tropic Thunder" stars Stiller as Tugg Speedman, who is shooting an action film when he and his co-stars are dropped into a real-life military conflict without their knowing. Downey Jr. plays Kirk Lazarus, a white actor who has a controversial procudure done so he can play black characters. The film opens nationwide on Wednesday, Aug. 13.