Act on what you are saying or stop talking about it, as in
You've been citing evidence for months but never presented it-now put up or shut up. This somewhat impolite term, often put as a command, is believed to come from gambling, in which a card player is told to ante up or withdraw. A second theory maintains that it means either put up your fists to fight or back down. [1870s] Also see
put one's money where one's mouth is.