Green’s Dictionary of Slang

hang v.5

(Aus./US drugs)

1. to be under the influence of drugs.

[US]L. Lipton Holy Barbarians 186: And he hits up the whole thing and he ... starts nodding, you know, hanging. And this other guy, ... he’s hanging.

2. to be in need of some drugs.

[US]B. Brunner Face of Night 232: Hanging—in distress for lack of narcotics. Also, ‘hung up’ [HDAS].
[Aus]L. Davies Candy 150: We were hanging like dogs, seriously edgy and sweaty.