Green’s Dictionary of Slang

(US) to curry favour with, to toady to.

1939		‘Citadel Gloss.’ in AS XIV:1 Feb. 24/1: a.k., v. To curry favor with a superior.
1947		C. Willingham End as a Man (1952) 252: The conversation shifted to a discussion of cadet military rank and how to be appointed to it. ‘Neatness.’ [...] ‘A.K.’ing.’.
1959		‘Gator (U. Fla.) Sl.’ AS XXXIV:2 154: A-K-ing (apple polishing).
1967–8		Baker et al. CUSS 69: AK [...] curry favor with a professor.
1971		I. Faust Willy Remembers 180: Bernier never even looked over, naturally a.k.’ing Dick Merriwell and Jack Armstrong.