Green’s Dictionary of Slang

hammerish adj.

[fig. use of SE hammer]

1. (US) drunk.

[US]B. Franklin ‘Drinkers Dictionary’ in Pennsylvania Gazette 6 Jan. in AS XII:2 91: They come to be well understood to signify plainly that A MAN IS DRUNK. [...] Hammerish.

2. very well aware.

[Aus]Vaux Vocab. of the Flash Lang.