Green’s Dictionary of Slang

1. to tell, to recount, thus gumbeat, n. a story, a speech.

1940		Pittsburgh Courier (PA) 27 Apr. 7/6: Lay a soft gum-beat in his receivers.
1944		D. Burley Orig. Hbk of Harlem Jive 42: Let me soft gumbeat thee a bedtime fable.

2. to chatter; thus gum-beating n., n. gum-beat, a talk.

1936		Archie Seale Man About Harlem 18 Apr. [synd. col.] [A] fine dinner breezed in and started to gumbeat with Cliff, the laughing soup mixer.
1938		Pittsburgh Courier (PA) 30 July 11/1: I will be glad when we cut into the Apple so you and I can get together and have a real old-fashioned gum-beat.
1940		Pittsburgh Courier (PA) 27 Apr. 7/6: Lesson 1: How to Collar a Chic. If the fowl is fly and doesn’t gum beat so sporty, try to drift to the donnie’s castle and skin-shake with the raisers.
1946		Mezzrow & Wolfe Really the Blues 77: They really came to listen, not to dance or gumbeat around the table.
1958		Hughes & Bontemps Book of Negro Folklore 484: gumbeat: To talk a lot, gossip. Women are always gumbeating.