Stop the presses! Hold everything!

Back in the days when newspapers were a more important and timely source of national and international happenings than they now are, their publishers made every effort to update news articles, even if it meant halting the printing process for a piece to be added or rewritten. When that happened, the cry “stop the presses” was heard, and the presses ground to a halt in mid-issue. You didn't have to be Perry White or Citizen Kane to shout “stop the presses!” All you had to do was mean you were about to say something of importance or, when meant sarcastically, to indicate that another person's statement was old news.