DMZ

a.k.a., Madame Psychosis

…like LSD that has itself dropped LSD…

Ed. note: DMZ is a fictional hallucinogen

Ultimate fate of the DMZ in the story? Not explicit? Believed: Hal obtains it (somehow) from Pemulis, takes it, and it causes a psychic meltdown of some form or another (hence the business with everyone misinterpretting his facial expressions and tone of voice).