> "The phrase originates from events in Jonestown, Guyana, on November 18, 1978, in which over 900 members of the Peoples Temple movement died. The movement's leader [...] Jones proposed "revolutionary suicide" by way of ingesting a powdered drink mix lethally laced with cyanide and other drugs which had been prepared by his aides."

TIL. I always thought the expression somehow referred to the drink itself, or perhaps its brand.