Green’s Dictionary of Slang

a despicable person or thing.

2004		IOL News (Western Cape) 12 Nov. 🌐 The soft porn rapture is naai [...] It gives you as much satisfaction as a teenager with a bad rash after an encounter of the bump-’n-grind-with-the-clothes-on kind.
2005		A. Lovejoy Acid Alex 77: Youse two!! You little naaiers. Fuck off from my house! [Ibid.] 212: He is the naai who put me in the bomb for three weeks.
2008		A. Lovejoy ‘The Smell of Tears’ at www.acidalex.com 🌐 3: The laaitie gangster naaiers he stole it [i.e. a gun] from will make his bones white if they find out.