What’s the deal with "yada yada yada"?

Welcome back to Pop Lexicon, The A.V. Club’s series with Kory Stamper, Merriam-Webster lexicographer and editor, where she reveals the origins of America’s favorite colloquialisms. Kory uncovers the roots of “yada yada yada,” a conversational shorthand popularized by Seinfeld—but it can be traced back even before color television.