tac, n. — Green’s Dictionary of Slang

tac n.

[PCP is a misappropriation of initials THC, i.e. tetrahydrocannabinol]

(drugs) phencyclidine.

1979		H. Feldman et al. Angel Dust 124: The large number of street names it has been accorded over the years: [...] tac.
2001		ONDCP Street Terms 21: TAC — PCP.
2007		R. Milward Apples (2023) 24: [A]ll I’d done before was tac at this girl’s house.