To walk the plank

	to walk along a plank laid across the bulwark of a ship, until one overbalances it and falls into the sea; - a method of disposing of captives practiced by pirates.
	to walk off the plank into the water and be drowned; - an expression derived from the practice of pirates who extended a plank from the side of a ship, and compelled those whom they would drown to walk off into the water; figuratively, to vacate an office by compulsion.- Bartlett.