Green’s Dictionary of Slang

to chat, to converse.

[1848		Paul Pry 27 Nov. n.p.: We advise J. H., of Bread-street-hill, not to wag his chin so much about the widder].
1869		J.C. Parkinson Places and People 92: They often walk in couples and even threes, too, smilin’ and chin-waggin’.
1906		Marvel 20 Oct. 365: Yes, do shut up! [...] I’m sick of your chin-wagging!
1913		E. Pugh Punch and Judy 138: If only we could tell what on earth they are all chinwagging about.
1925		N. Lucas Autobiog. of a Thief 71: Come where we can chin-wag.
1933		J. Spenser Limey 34: We didn’t stop for jollifications and chin-waggings.
1952		A.W. Upfield New Shoe 98: Come in and sit you down and chin-wag awhile.
1991		R. Doyle Van (1998) 409: He’d sat on that stone bench with the two bronze oul’ ones chin-wagging on it.
1997		P. Theroux Kowloon Tong 52: Here I am chin-wagging and I fancy you want your beer.