(chiefly British) to perform an action that will cause extreme agitation, nervousness, discord, or other states characterized by frantic activity; such an action is unlikely to have a productive outcome unless chaos itself is the desired end, as in: “I wouldn’t send the cost-cutting consultants out to meet the rank-and-file unless you want to set the cat among the pigeons”; evokes the terror of defenseless birds when faced with the sudden nearness of their deadliest enemy; can be done intentionally as a power-demonstrating move by those who have less of it than they think