gape, v. — Green’s Dictionary of Slang

gape v.

[gap v. (2); the yawning that is typical of an addict suffering from withdrawal]

(drugs) to go through withdrawal; thus gaping n., the desire for narcotics.

1953		‘William Lee’ Junkie (1966) 159: Sick, Gaping, Yenning . . . Sickness caused by lack of junk.
1969		R.R. Lingeman Drugs from A to Z (1970) 100: gaping [...] Experiencing opiate (heroin) withdrawal symptoms.
1971		E.E. Landy Underground Dict. (1972) 86: gape. [...] Go through withdrawal symptoms, usually from an opiate.