In Hot Water

First used figuratively as early as the 1530s, with the exact origin genuinely uncertain even that far back. Several competing theories exist. One simply points to cooking: being plunged into hot water means being boiled, an intuitively unpleasant fate. Another ties it to medieval trial by ordeal, where an accused person's arm might be plunged into boiling water, with a clean, fast-healing burn taken as a sign of innocence. A third theory points to the old defensive practice of pouring boiling water down from castle walls or upper windows onto unwanted visitors, an unambiguous, painful way of saying "leave." No single theory has ever been confirmed over the others.