The Unholy Three (1930)

Professor Echo is a sideshow ventriloquist who recruits two sociopathic co-workers, Midge and Hercules, the show's midget and strong man respectively, into a burglary ring. Echo disguises himself as the elderly Mrs. O'Grady, the owner of a pet store, who sells talking parrots and mynah birds to a high-class clientèle with Hercules posing as his son-in-law married to Echo's pickpocket girlfriend Rosie and Midge passing as their infant son. Echo's ventriloquist skills initially convince the customers that their parrot can talk, but they're disappointed when they bring the mute bird home. A phone call of complaint brings Grandma O'Grady and her daughter's "baby" to the client's house to facilitate the bird's talking, an opportunity to case the house for a subsequent robbery by "The Unholy Three."