There's a pretty strict level of decorum you're supposed to maintain on a commercial flight. For example, you're not allowed to smear feces on any of the cabin walls. Wearing an obnoxious amount of clothing to avoid checking a bag will not endear you to the flight staff, either.
The same goes for running through a plane completely naked. An Alaska Airlines passenger was reportedly detained after doing exactly that on Monday. The New York Daily News reports that a man onboard Alaskan Airlines flight 107 from Seattle to Anchorage ran around the plane's aisles for 20 minutes sans clothing. He was eventually tackled and locked in a bathroom by two passengers who'd seen enough of him. The naked man was reportedly apprehended by authorities and taken to a nearby hospital.
Johnny Ellis, a former Alaska state senator and state representative, was onboard the flight and tweeted what he saw: