Green’s Dictionary of Slang

shermed (up) adj.

[see sherm n.]

(US black/drugs ) intoxicated by phencyclidine.

[US]T.R. Houser Central Sl. 47: shermed-up To be loaded or high on PCP.
[US]L.A. Times 31 May 328/4: I’m thinking this guy is so shermed he doesn’t even know what he ’s doing.