Green’s Dictionary of Slang

sherm n.

also shermans, sherms, sherm stick
[the smoking of Sherman cigarettes laced with phencyclidine]
[1980s+] (US black/drugs)

1. phencyclidine; thus shermed (up) adj., intoxicated.

2. embalming fluid, formaldehyde [note William Shaw, Westsiders (2000): ‘It probably acquired the name sherm when users started dipping Sherman cigarettes in the fluid, choosing the brand because its cigarettes are more robustly constructed than most and don’t fall apart when steeped in fluid’].

In compounds

shermhead (n.) [-head sfx (3)]

[1990s+] (US drugs) one who is addicted to marijuana or plain cigarettes dipped in PCP.

sherm stick (n.) [stick n. (6a)]

[1980s+] (US black/drugs) a plain cigarette or one composed of marijuana, laced with phencyclidine.