Green’s Dictionary of Slang

1. the proper name Sidney.

1969		S.T. Kendall Up the Frog 11: ’Ave a butcher’s ’ook at Steak and Kidney, ’e’s elephants trunk!
1996		(con. 1964-65) B. Thorpe Sex and Thugs and Rock ’n’ Roll 1: King’s Cross [...] The Cross, the ‘Irish Moss’ — or just the ‘Irish’ in ‘Steak and Kidney’.

2. (Aus., also steak and kid) Sydney.

1945		Baker Aus. Lang.
1951		Cusack & James Come in Spinner (1960) 329: Gawd, it’s good to hit the old Steak-and-Kid again.
1954		Sydney Morn. Herald 8 Nov. 2/4: Just come down from steak-and-kidney, eh?
1967		‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxix 4/5: steak and kidney: Sydney.
1983		R. Aven-Bray Ridgey-Didge Oz Jack Lang 45: Steak and Kidney Sydney.
1989		R.G. Barrett Boys from Binjiwunyawunya 11: That rather large,bustling city between Newcastle and Wollongong known affectionately as ‘The Old Steak and Kidney’.
1998		R.G. Barrett Goodoo Goodoo 188: A couple of days in Cairns lying around in the sun before I head back to the old steak and kidney.
1999		G. Seal Lingo 91: steak and kidney is Sydney.
2002		Pete’s Aussie Sl. Home Page 🌐 steak and kidney: Sydney.