The McRib.Photo by David Paul Morris/Getty Images McDonald's is bringing back the McRib nationally for a farewell tour. The McRib has had at least three other farewell tours, and its been on and off menus since 1981. The McRib drives traffic and sales for McDonald's whenever it returns, and the CEO called it the "GOAT of sandwiches." The McRib only exists because of the success of another iconic McDonald's menu item: McNuggets.Spicy McNuggets.McDonald'sSource: InsiderAfter McNuggets were introduced in 1979, franchisees couldn't get enough of them and demanded another hot product to sell.Hollis Johnson/Business InsiderSource: InsiderExecutive chef Rene Arend was inspired to create the McRib after a trip to South Carolina where he ate barbecue.Facebook/Hecky's BarbecueSource: MaximThe design for the McRib used new technology for "restructured meat product" created by Richard Mandigo at the University of Nebraska.Photo by NICHOLAS YEO/AFP via Getty ImagesSource: NPRThough it contains little rib meat, Arend designed the shape to "look like a slab of ribs."McDonald'sSource: MaximThe McRib officially debuted in test markets in 1981, expanding further in 1982.McDonald'sSource: RetroistMcDonald's used an extensive advertising campaign to explain it to customers.