The story
From a scene in the film Scarface (1983), in which drug dealer Tony Montana (Al Pacino) is mocked for excessively consuming cocaine from his own inventory. : 1983, Oliver Stone, Scarface, spoken by Elvira Hancock (Michelle Pfeiffer): Lesson number two: Don't get high on your own supply.
Etymology from Wiktionary, CC BY-SA 4.0.