One is faced with imminent danger or trouble. In Greek mythology, the courtier Damocles was forced to sit beneath a sword suspended by a single hair to emphasize the instability of a king's fortunes. I know how irritable and unpredictable the boss can be, so I feel like Damocles' sword hangs over my head whenever I'm alone with him. With the threat of nuclear war, many feel that Damocles' sword is hanging over the entire world's head.