The Muppet Show - Season 1 Episode 13 -

Kermit begins to worry that guest star Harvey Korman isn’t having a great time because he complains of being the “token person” on the show with all the dogs, frogs, pigs and chickens as well as the fear of hoof-and-mouth disease. So the rest of the Muppets come up with a solution: dress Harvey in a chicken suit.