Green’s Dictionary of Slang

hack v.4

[hack n.3 ]

(US Und.) to work as a night watchman.

[US]Jackson & Hellyer Vocab. Criminal Sl. 42: hack [...] used as a verb in the past participle it describes the accomplished function of a night watchman. Example: ‘The joints hacked but not kipped,’ i.e., watched but not occupied by a sleeper.