off the cuff   (TTS發音)

without preparing ahead of time what one will say無準備地；即興地

    He is always at his best when he speaks off the cuff. 他即席講話總是講得很出色。

    Considering that the speech was off the cuff，it was rather good. 由于這發言是毫無準備的，所以它還算是不錯的。