Rob McElhenney’s transformation on It’s Always Sunny in Philadelphia from Fat Mac to Jacked Mac is well-worn terrain. First, here’s the origins story of Fat Mac: Ahead of the 2011 season of It’s Always Sunny, Rob McElhenney was editing an episode. During the course of that episode, he saw himself in a shot and thought, “That’s not a good angle of me,” and considered finding a different shot that made him look better.