Green’s Dictionary of Slang

(drugs) mescaline.

1959		Kerouac letter 6 Oct. in Charters II (1999) 219: Okay for mescal, be in soon.
1966		M. Rumaker Exit 3 and Other Stories 139: I’ll get you some mescal and maybe that’ll warm up your pipes.
1974		P. Gent North Dallas Forty 221: Did I really eat the worm at the bottom of that bottle of mescal?
2001		ONDCP Street Terms 15: Mescal — Mescaline.