Shoot One's Mouth Off Meaning

Example : 1943, David Deutsch, "Heard in the Lobbies," The Canadian Jewish Chronicle, 16 July, (retrieved 7 Jan. 2010):  George Jessel . . . is still shooting his mouth off as though nothing mattered except his own gift for wise-cracks.2004, Alex Witchel, "The Salon Keeper," New York Times, 28 March, (retrieved 7 Jan. 2010):  I never shot my mouth off, I was quiet and I listened.