Green’s Dictionary of Slang

1. (also yakkapukee) talk, chatter.

1882		Sydney Sl. Dict. (2 edn) 9: Yacker - Talk.
1940		E. Curry Hysterical Hist. of Aus. 48: He [...] suggested that they should do their uttermost to get the boys and girls started on a gentle yakker.
1971		T. Thackrey Thief 228: What’s all this yakkapukee you putting about being a pall bearer at my funeral?
2006		D. Mitchell Black Swan Green 286: All yackewring yackerly to be heard over the yackering yacker.

2. a gossip, one who talks too much.

1960		Kerouac letter 20 June in Charters II (1999) 259: In the past he scorned me for being a drunken yakker.
2004		Mad mag. Jan. 40: The controversial right-wing yakker opened up his big fat trap.