Green’s Dictionary of Slang

highcoct adj.

(Aus.) in good spirits, cheerful.

[Aus]Hamilton Spectator (Vic.) 7 Jan. 1/7: If you ask him how he is, he is ‘all serene,’ ‘jolly,’ ‘ highcoct’ ‘ spotty ;’ perhaps he may be ‘out of sorts,’ ‘down in the mouth,’ ‘seedy’.