呼之即来，挥之即去
At one's beck and call.

eg:The boss has many workers at his beck and call around him.

中英俚语俗语来源：苏轼 王仲仪真赞序：“至于缓急之际，决大策，安大众，呼之即来，挥之即散者，唯世臣巨室为能。”

同义词：颐指气使 Get someone by the short hairs.