Green’s Dictionary of Slang

1. (also chattertrap) the mouth or tongue.

1818		M.L. Weems Drunkard’s Looking Glass (1929) 61: Oh! that eternal chatter box his tongue!
1825		Pierce Egan’s Life in London 12 June 157/2: Neale hit Cullen, right and left, on the chatter-box.
1842		Flash (N.Y.) 10 July 2/2: Murphy got it again on his chatterbox.
1857		Bell’s Life in Victoria (Melbourne) 2 May 4/1: He received a nasty one on the chattertrap.

2. a car radio; thus chatterbox and fish pole, a radio and aerial.

1941		Detroit News 16 Mar. in AS XVI:3 240: chatterbox and fish pole. Car radio and aerial.
1941		in Mencken Amer. Lang. Supplement II (1948) 724: Chatterbox. A car radio.

3. a machinegun.

1940		Mail (Adelaide) 22 June 23/1: In the AIF. a Lewis gun is called a ‘chatterbox’.
1949		Monteleone Criminal Sl. (rev. edn).
1955		‘Blackie’ Audett Rap Sheet 115: First off, we needed us some machine guns [...] Homer he was fresh out of a chatterbox, too.

4. (US Und.) a typewriter.

1950

Goldin et al. DAUL 42/2: Chatterbox. 1. A typewriter.

5. a walkie-talkie.

1962

H. Livings Nil Carborundum (1963) Act III: There’s that rotten nit again with his chatterbox.