磨嘴

to argue pointlessly / to talk incessant nonsense / to blather

to rub / to grind / to polish / to sharpen / to wear down / to die out / to waste time / to pester / to insist

grindstone / to grind / to turn round

mouth / beak / nozzle / spout (of teapot etc) / CL:張|张[zhang1],個|个[ge4]

to wear out the skin of one's teeth (idiom); pointlessly blather / to talk incessant nonsense / blah blah