Green’s Dictionary of Slang

(drugs) phencyclidine.

1979		H. Feldman et al. Angel Dust 111: They had no difficulty in acquiring the drug and ‘pushed’ ‘CJ,’ or marihuana joints laced with PCP dust.
1981		D.E. Miller Bk of Jargon 337: CJ: PCP.
2001		Da Smokehouse Marijuana Gloss. 🌐 cj- crystal joint.