beat one's gums

beat one's gums  {v. phr.},  {slang}

To engage in idle talk, or meaningless chatter; generally to talk too much.

"Stop beating your gums, Jack," Joe cried. "I am falling asleep."

Compare:

CHEW THE FAT or CHEW THE RAG,

SHOOT THE BREEZE or BAT THE BREEZE or FAN THE BREEZE or SHOOT THE BULL.