Good Old-Fashioned Nightmare Fuel, a term coined by MST3K, refers to a substance with extensive creeping-people-out properties. Nightmare Fuel can be processed from anything generally scary; among the things it is said to be produced from include grease from HAL 9000, the green light from Moonscar Island, Yellow Lantern light, Angel blood, and the bodily fluids of whoever thought The Inheritance Cycle was a good idea. The substance takes the form of glowing green stuff that is collected in vials and researched by the PPC.
Exposure to Nightmare fuel can freak people out for several hours, and direct consumption of it can result in a catatonic state. Higher-ranked Agents have been known to jestingly threaten their subordinates with the stuff when they slack off.