Empires have risen and fallen via a single bullet. (Just ask Archduke Franz Ferdinand.) In this case, the shot was fired from a .38 caliber pistol in the California desert, on a warm day in January 1998. The finger on the trigger belonged to Philip John Clapp, better known by his stage name: Johnny Knoxville . He was also the victim. P.J., as his friends called him, was going to test out a bulletproof vest. He strapped on some Kevlar, stuffed some copies of Hustler under his shirt for extra “