"Drinking the Kool-Aid" is a metaphor, used in the United States and Canada, that means to become an unquestioning believer in some ideology, or to accept an argument or philosophy wholeheartedly or blindly without critical examination. The phrase can sometimes have a negative connotation, or can be used ironically. The basis of the term is a reference to the November 1978 Jonestown Massacre,[1][2] where members of the Peoples Temple were said to have committed suicide by drinking a "Kool-Aid"-like drink laced with cyanide.[3]
Evidence gathered at the Jonestown site after the incident indicated that Flavor Aid (a similar powdered drink mix), not Kool-Aid, was used in the massacre. Some survivors of the incident object to the link between blind faith and the deaths of members of the People's Temple implied by the phrase, because some victims were murdered—forced to drink at gunpoint—rather than being convinced or forced to commit suicide. In addition, Jim Jones had previously had many rehearsals for the event in which the drink contained no poison, which led to cult members believing the drink was harmless on the day that it did contain poison[4]
Objections notwithstanding, the phrase is commonly used in a variety of contexts to describe blind, uncritical acceptance or following.