Expert drug dealer or drug user who provides quality info about drug use. A go-to-person for drugs and usage instructions; one who is especially good at maximizing fun and ensuring safety.
The black market equivalent of a real anesthesiologist.
"I never do hard drugs without first consulting my anesthesiologist."
"I thought the pill was a dud, but my anesthesiologist told me to wait another hour before taking another. He was right on."