Green’s Dictionary of Slang

1. a woman who participates in sex with multiple men.

1985

Tracks (Aus.) Oct. 82: The one that roots is fourteen. The gangy is thirteen. And the head job is twelve [Moore 1993].

2. the act of gang rape.

1985		‘Thommo’ Dict. Aus. Swearing & Sex Sayings 57: GANGIE — Where a female is singled out by a group of males for intercourse by all of them.
2003		McGill Reed Dict. of N.Z. Sl. 84: gangie/gangbang/gangbash/gangsplash Serial female rape. ANZ.

3. a gang member.

2002

A. Duff Jake’s Long Shadow 70: Life in jail is bad. [...] You do minimum ten years, more if you’re a gangie.