Actress Maureen McCormick, best known for her iconic role as Marcia Brady, is boycotting the new comedy "Tropic Thunder" because it uses the R-word ("retard").

"I know Ben Stiller has said that he's making fun of actors, not people with disabilities. Still, the movie is geared toward a younger crowd, and I fear a lot of those teenagers ... will leave the theater thinking "retard is an OK word to use," McCormick writes in a blog entry on

"I have a mentally handicapped brother, and when we were growing up all I heard was the word "retard," she said. "People called him that and other cruel names. ... It was terribly painful for both of us."