Any really really dumb mistake that is both personally devastating or painful and publicly humiliating. In reference to Plaxico Burress shooting himself in the leg.
Steve: Did you see that Plaxico Burress shot himself in the leg? What an idiot!
James: Yea, what an awful plaxident.
Andy: I was running the other day across the street and tripped over myself, falling in front of a bunch of people who laughed at me. It was the worst plaxident of my life.