A well-known image built around a well-known barb, in this case the heckling of a black minister. 'Pull Down Your Vest,' says the heckler--in this case a parrot, seated behind the minister. "Pull down your vest" was a common joke phrase used to throw a speaker off his train of thought. It was used by Mark Twain in his 1880 story 'Jim Baker's Blue Jay Jam.' The Dictionary of Slang, Jargon and Cant says it come from the habit of one's vest 'riding' up and exposing one's shirt or belly. Mothers would say to their sons 'pull up your vest.' It also means 'mind your own business.'
