Green’s Dictionary of Slang

(drugs) a limited or occasional use of drugs.

1967		P. Thomas Down These Mean Streets (1970) 200: I never figured on getting hooked all the way. I was only gonna play it for a Pepsi-Cola kick.
1978		(con. 1965) J. Carroll The Basketball Diaries 92: I’m gonna be fifteen soon and the summer’s ‘Pepsi-Cola’ heroin habit is tightening more and more around me. [...] A ‘Pepsi-Cola’ is a small habit, a first habit that finally sneaks up on you.
2001		ONDCP Street Terms 16: Pepsi habit — Occasional use of drugs.