Had an early morning commercial flight back from Denver today. Flightaware has a cool feature that lets you look up a commercial flight and load the filed flight plan into Foreflight, and this is what came up. KDEN PYPER BGD POTTY KDFW After take off and flying the departure, we made it to PYPER and then headed towards BGD. Sometime before we made the VOR, the pilot hung a left and headed directly to the next waypoint. As someone that has just started studying for my IR, I was wondering if this was something that ATC would have just done, or if there were other ways this might have come about? If this was assigned by ATC, somebody please tell the 13yo in me that at sometime this morning there was a controller that had to utter the phrase "Frontier 124 proceed direct to POTTY" or something like that.