on the button
精確無誤、準確到位
口語·強調時間或動作精確無誤
英文釋義
at exactly the right time or in exactly the right way
例句
He arrived at 3 o'clock on the button, just as promised.
典故來源
可能源自拳擊比賽中擊中按鈕（button）即得分，或與精確計時器按鈕有關，強調準確性。