Green’s Dictionary of Slang

(Aus.) a quick wash of ‘important’ areas of the body.

1982		N. Keesing Lily on the Dustbin 31: The APC belongs to an order of Sheilaspeak that allows members of a group who understand it to convey information to each other.
1991		J.T. Pickle Aus.-Amer. Dict. 11: APC: Not a headache remedy but a quick bath of the arm pits and crotch.