Columbo episode called The Conspirators. In it the murderer, a man called Joe Devlin, likes to drink whiskey. He's careful not to like drinking whiskey too much though, so before drinking he uses a diamond (set into a ring) to mark the side of the whiskey bottle. As Devlin makes the mark he says "This far and no farther". Once the level drops to the mark he stops drinking. Thus Devlin is making use of a WIP limit - a Whiskey In Progress limit.