The Death Card
As the legend has it, the ace of spades was being left by the American troops during the Vietnam war on dead bodies of those whom they had killed. They were also used to scare away Viet Congs soldiers without firefight since the latter believed a spade, according to the Vietnamese tradition, to be a herald of death and ill-fortune. In Coppola's 'Apocalypse Now' one of the American soldiers (presumably played by Robert Duvall) throws such a card onto the lifeless body of some Vietnamese.