a flutter in the dovecote

A stir or mild disturbance among a certain organization or group of people, especially one that is typically quiet, reserved, or conservative in nature. Likened to domestic pigeons fluttering their wings in response to an agitation (a dovecote being a structure built to house and raise them). The unexpected entrance of an exuberant young woman caused a bit of a flutter in the dovecote at the old Men's Only club.