Green’s Dictionary of Slang

1. (Aus./N.Z., also coight, coit) the anus, the buttocks; thus go for one’s quoit(s), to hurry.

c.1919		Yellow Rag in P. Adam-Smith Folklore of the Aus. Railwaymen 236: STEWARD’s CHORUS / We expect our Upright Grand Instrument out by this afternoon’s delivery. Also, Quoits, Balls, and Games / FUN FOR EVERYONE / that can make fun.
1941		Baker Popular Dict. Aus. Sl. 58: Quoit, the buttocks.
1951		(con. 1941) E. Lambert Twenty Thousand Thieves 95: See those jokers sitting on their quoits over there?
1967		‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxviii 10/3: quoit: Backside.
1985		R.G. Barrett You Wouldn’t Be Dead for Quids (1989) 128: You’ve been tight as a tom-cat’s quoit since the day you were born.
2002		S. Maloney Something Fishy (2006) 18: You know much i enjoy sitting on the backbench with my thumb up my quoit.
2007		S. Maloney Sucked In 52: We’d better be ready. not sitting around with cobwebs up our quoit.
2016		N. Cummins Adventures of the Honey Badger [ebook] The poor girl was walking on the old boy’s back while hanging onto the tops of the partition and misjudged her step while working on the coight region.
2016		N. Cummins Adventures of the Honey Badger [ebook] You couldn’t drive a pin up his arse with a sledgehammer. Mate, he is as tight as a fish’s coit.

2. (Aus.) the female genitals.

c.1943

S.J. Baker Aus. Vulgarisms [t/s] 12: quoit: The female pudend.

3. (Aus.) a fool.

1945

Baker Aus. Lang. 130: Fools of one kind and another have carved a considerable niche for themselves in Australian speech and little explanation is needed for any of the following: lardhead, loop, nit, plat (a clipping from platypus), quoit [etc.].