6. 'How Mac Got Fat' (Season 7, Episode 10)
Rob McElhenny has offered several explanations for why he decided to gain a bunch of weight before his show's seventh season, but the simplest reason is the one that makes the most sense: Fat Mac is hilarious. For the better part of 10 episodes, the character's added bulk is barely mentioned. Then, almost out of the blue, "How Mac Got Fat" presents an extended flashback — mostly salvaged from an unaired sixth season episode — that recalls a time when Paddy's became successful and the gang all picked up strange hobbies and appetites. Though not as overtly self-referential as some episodes, this overdue origin story examines how complacency sets in after the underdogs actually win.