Green’s Dictionary of Slang

1. anything exceptionally good.

1984		Partridge DSUE (8th edn) 988/1: since ca. 1920.
1999		R.G. Barrett Wind & Monkey (2013) [ebook] ‘Digger’s half in the rort [i.e. the discovery of treasure]’.
2003		McGill Reed Dict. of N.Z. Sl. 175: rort [...] 2. Something exceptional, often a party, called also a rorter.

2. (Aus.) a crowd.

1923		Smith’s Wkly (Sydney) 2 June 21/2: His strength was handy in pushing up, in a ‘rort,’ otherwise he was useless.
1938		Smith’s Wkly 21 May 6/4: I remember meeting [...] ‘Tibby,’ greatest of all Australian ‘whizzmen’ (pickpockets). [...] ‘Blime,’ he roared, ‘I been working with a gay (mug), and taking risks in the ‘rort’ (crowd) for a ‘bloodhoon’ who never lifted a ‘leather’ (wallet) in his life’.
1941		Baker Popular Dict. Aus. Sl. 61: Rort, [...] a crowd.

3. a wild, noisy party; also attrib.

1942		Truth (Sydney) 5 July 17/1: At the very commencement of the ball Mrs. Devine speechified. Said she: ‘Now I don't want this to be a rort. If anybody puts on a blue I’ll hoist ’em out’.
1946		Truth (Sydney) 11 Aug. 1/1: From what I have heard — and, boy, I have heard plenty — the party developed into a rort; a real humdinger, hold-your-hat-on, rort.
1950		T. Devine in Blaikie Remember Smith’s Weekly? (1966) 217: Don’t any of youse put on a blue or make a rort out of my house.
1969		A. Buzo Rooted III iv: It’s going to be a real rort. Everyone’s coming [...] It’ll be the turn of the century.
1972		J. McNeill Old Familiar Juice (1973) 93: bulla: Righto then let’s get a bit er melody in the rort!
1988		Canberra Times (ACT) 10 Nov. 29/2: The evening was supposed to be co-hosted by winemaker Mark Cashmore who didn't make it [...] someone ought to tell him he missed a real good rort.
1997		Bug (Aus.) 1 Oct. 🌐 At least some federal public servants were thinking straight when they stuck it to Howard by opening up the touted travel rorts affair.
2003		see sense 1.