CEDAR RAPIDS - A controversial movie opened in theaters across the country Wednesday. Advocates for people with disabilities are speaking out against the action comedy "Tropic Thunder." The movie has a lot of big names, Ben Stiller, Jack Black, and Robert Downey Junior. It's getting good reviews. Roger Ebert gave it a three and a half out of four stars. But one group wants movie-goers to boycott the film because it includes what they call the "r" word.

Some eastern Iowa parents of children with down syndrome say the size of a protest doesn't matter when you're protecting your children from pain.

"It's a demeaning word, just like a racial slur would be," says Troy McCarthy.

McCarthy, father of nine-year-old Nathan, is talking about the frequent use of the word "retard" in the new action comedy, "Tropic Thunder".

"You aren't full retard, never go full retard," is one line from the movie.

The McCarthys, along with more than a dozen other members of the Hawkeye Area Down Syndrome Association,or HADSA, passed along a simple message to Wehrenberg movie-goers and rush hour drivers on Council Street.

"Don't say the "r" word. It's not nice," says Nathan.

Film co-writer and director Ben Stiller says the use of the word retard was not meant to offend anyone. Rather, actors use the word to refer to Stiller's character, Simple Jack.

"There were times I was doing Jack when I actually felt retarded, like really retarded in a weird way I had to free myself up to believe I'm not stupid or dumb," Stiller says in the movie.

Nathan's twin brother, Gabe, hopes others follow their lead and boycott the movie.

"I want people to support my brother, literally he's my brother," says Gabe.

HADSA members hope several small protests across the country will keep people out of "Tropic Thunder" theaters.

DreamWorks Pictures, the production company that released the R-rated movie, says no changes will be made to the movie. And that the film is in no way meant to harm the image of individuals with disabilities.