A person who does not partake in the smoking of marijuana, and willing to call the police on others who do. The term is usually yelled among stoners when a police-informant is in the area and can visibly see or smell the group.
Mitch: "I just got a new RA"
Me: "Watch out. He's a stoner nazi"
Mitch: "Shit! I can't smoke in my room anymore"