eating air
When someone flaps their jaws like a fish out of water while talking, making it look like they’re chewing invisible snacks and probably have no idea what they’re saying.
My cousin’s eating air so hard during his speech, I thought he was trying to swallow the microphone.
At the bus stop, this guy was eating air so loud, the whole neighborhood thought there was a food fight.
My teacher said I was eating air during the test, but I was just chewing my pencil to death.