The Special Olympics and 21 other disability groups are calling for a nationwide boycott of the new Ben Stiller-directed film Tropic Thunder over what the groups consider a “negative portrayal” of the developmentally disabled.

“We are asking people not to go to the movie and hope to bring a consciousness to people about using derogatory words about this population,” Peter Wheeler, spokesman for the Special Olympics, said Monday.

Tonight’s Tropic Thunder Hollywood will be “the start of a nationwide protest,” Wheeler says.