Green’s Dictionary of Slang

hostile adj.

In phrases

go hostile (at) (v.) (also go hostile on) [orig. Aus./N.Z. milit. use]

1. (US tramp) used of places or individuals considered unfriendly (often aggressively so) to hobos.

[US]Morn. Tulsa Dly World (OK) 13 June 19/2: Hostile — Referred to towns or police that are brutal and mean to hobos.
[US] ‘Gila Monster Route’ in N. Anderson Hobo 195: He thought of the time he lost his pal / In the hostile berg of Stockton, Cal.
[US]J. Black You Can’t Win 69: Better wait till night if you want to make a train. The railroad bull is hostile.
[US]‘Boxcar Bertha’ Sister of the Road (1975) 33: The shacks are hostile, and the railroad dicks will glom you sure, unless you’re lucky.

2. (Aus.) to become angry (with).

[Aus]K. Tennant Battlers 90: They won’t stick together [...] scared a John ’ud go hostile on them.
[NZ]McGill Dict. of Kiwi Sl. 51/1: go hostile act angrily; eg ‘If he says one more word to her, I’ll really go hostile.’.
[NZ]McGill Reed Dict. of N.Z. Sl. [as cit. 1988].