flap (one's) jaws(redirected from flapping their jaws)
flap (one's) jaws
To talk in a meaningless, aimless, or idle manner; to chatter or blather. Jim always starts flapping his jaws after he's had a couple of drinks. Quit flapping your jaws—I need some quiet so I can think!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.