Green’s Dictionary of Slang

(Aus./N.Z.) awake, aware; one who is aware.

1967		‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxiii 4/4: currant cake: Awake.
1983		R. Aven-Bray Ridgey-Didge Oz Jack Lang 22: Currant Cake Awake.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 50/2: currant cake adj. and n. awake, aware, informed.