beat (one's) gums
To talk repeatedly and/or lengthily but without impact. I constantly beat my gums about dirty dishes in the sink, and the kids still never clean up after themselves!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
beat one's gums
to waste time talking a great deal without results. (As if one were toothless.) I'm tired of beating my gums about this over and over. You're just beating your gums. No one is listening.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.