This is a challenge to the hierarchy that has ruled American fast food since it was invented: Burgers were the core product, and when fried chicken was available at all, such as at KFC, it tended to come bone-in, or as nuggets or tenders or “popcorn.” Nick Wiger, who with Mike Mitchell hosts a comedy podcast about fast food called Doughboys, doesn’t remember eating many fried-chicken sandwiches when he was growing up in Southern California, in the ’80s and ’90s. To the degree that he did, he told me, they “were like the add-on sandwich, the bonus sandwich”—the sideshow to the main event, which was usually a hamburger.