Green’s Dictionary of Slang

(Aus./N.Z.) the best, the ultimate, the ideal.

1924		Truth (Sydney) 27 Apr. 6/5: Grouse, something good.
1938		Partridge DSUE (2nd edn).
1944		T. Hartley glossary in Simes DAUS (1993) 98/2: [...] ‘this is a grouse yarn.’ ‘Boy! Its the grouse!’ Takes on a special meaning in gaol where tobacco, tea etc is of rather poor quality so that anything smuggled in from outside is automatically known as ‘the Grouse.’ It is the most popular term of acclamation used.
1974		J. McNeil How Does Your Garden Grow Act III: If yer gonna dream, well yer might as well order the grouse, hey?
1982		Bulletin 12 Jan. 10: ‘Grouse’ was used in three forms [...] finally, the superlative degree 3. the grouse, as in ‘I reckon a cold beer on a scorcheer like this would be the grouse!’.
1989		R.G. Barrett Boys from Binjiwunyawunya 59: ‘You don’t mind this piloting rort, do you’ [...] ‘Mate, there’s nothing like it [...] It’s the grouse’.
1991		R.G. Barrett Between the Devlin 47: The roast beef was the grouse.
2001		(con. 1945–6) P. Doyle Devil’s Jump (2008) 11: Dancing in the park, [...] good music playing, not a copper in sight – this really is the grouse, I thought.
2002		R.G. Barrett Mystery Bay Blues 60: The old white joint. It’s the grouse.