n. a technique typically used by law enforcement wherein the wooden baton - traditionally made of wood from the hickory tree - is applied on or about the head and shoulders of a deserving miscreant resisting arrest or otherwise needing a lesson.
COP 1: "Last night, some drunk dude wanted to fight when I went to arrest him. Now he's in the hospital getting his teeth re-aligned."
COP 2: "How'd you get him?"
COP 1: "Gave him the ol' hickory shampoo."
COP 2: "Damn..."