Green’s Dictionary of Slang

onka n.

also onkaparinga
[rhy. sl.; ult. Onkaparinga, the brandname of a make of woollen blanket; note Charleston (WV) Daily Mail 20/1/1935: ‘Onkapringa – More Chinese, or something. Means “good”.’]

(Aus.) a finger.

Show quotations
[Aus]Mail (Adelaide) 16 Feb. 1/4: This is how a class of rhyming ‘slangsters’ [...] discourse on anatomy:— Fingers— Onkaparingas or jolly jingoes.
[Aus] ‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxviii 10/1: onkaparingas: Fingers.
[Aus]Bulletin (Sydney) 26 Apr. 46: Rhyming slang did filter through into the idiom, but the knock-abouts quickly turned most of the phrases into shortened versions – [...] egg (short for egg and spoon: hoon, or prostitute’s pimp); onka (short for Onkaparinga: finger).
[Aus]R. Aven-Bray Ridgey-Didge Oz Jack Lang 9: It seemed like no time at all that her Onkarparingas had slipped a Dunlop overcoat on his eight-day-clock and the contract had been fulfilled.
[Aus]Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Onkaparinga. Rhyming slang for finger.
[Aus]Pete’s Aussie Sl. Home Page 🌐 Onkaparinga, Onka: a finger.
[Aus]T. Peacock More You Bet 46: Notes should be flicked over [...] and not walked through with the fingers only (or in rhyming slang, ‘the onkaparingas, or ‘onkas’ for short).