Green’s Dictionary of Slang

(orig. US) incessant, frivolous, tedious chatter; also as adj.

1936		‘Hectic Harlem’ in N.Y. Amsterdam News 8 Feb, sect. 2 n.p.: GUM BEATIN’. – Talking irrelevant and without fact [...] GUM KNOCKIN’ – Same.
1941		D. Burley N.Y. Amsterdam Star-News 26 Apr. 13: [headline] Department of Gum Beating.
1953		F. Paley Rumble on the Docks (1955) 21: And he wasn’t like his mother, taking his father’s blows and gum-beating all the time.
1954		Mad mag. May 4: Enough gum-beating, Zark ... we’ve got to go find our rocket ship.
1957		(con. 1943) A. Myrer Big War 5: Now let’s not have any gum-beating about it.
1960		(con. 1950) R. Leckie March to Glory (1962) 22: He had grinned to hear them grumble, for Barber knew that gum-beating Marines are hard to lick.
1992		R.C. Cruz Straight Outta Compton 17: Gum-beating. Going for soul. Giving out.