Green’s Dictionary of Slang

chat n.4

[chats n.2 ]

(Aus.) a general insult, usu. aimed at an old man, esp. an alcoholic.

[Aus]Stephens & O’Brien Materials for a Dict. of Aus. Sl. [unpub. ms.] 43: CHAT: Austral. thieves man.
[Aus] ‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxiii 4/3: chat: [...] A term used to describe an obnoxious person.
[Aus]Adamson & Hanford Zimmer’s Essay 46: A chat who smelt of white lady swilled and puked. [Ibid.] 99: In New South Wales prison argot, it means both ‘louse’ and a certain type of prisoner. A ‘chat’ is a social incompetent, though not necessarily drunk.
[Aus]R. Aven-Bray Ridgey-Didge Oz Jack Lang 22: Chat Derelict person.
[Aus]Tupper & Wortley Aus. Prison Sl. Gloss. [Internet] Chat. A person who is a [sic] sloppy or dirty in their habits or dress. Often applied to vagrants serving short sentences.

In compounds

chat’s yard (n.)

that area of a prison reserved for tramps and other derelicts.

[Aus] ‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxiii 4/3: chats’ yard: The section of prison where grubby people are segregated.
[Aus]R. Aven-Bray Ridgey-Didge Oz Jack Lang 23: Chat’s Yard Derelict person’s section of a prison.
[Aus]Tupper & Wortley Aus. Prison Sl. Gloss. [Internet] The ‘chat’s yard’ is part of a prison reserved for derelicts.