1968, acronym from fictitious "Youth International Party," modeled on hippie.
On December 31, 1967, Abbie [Hoffman], Jerry [Rubin], Paul Krassner, Dick Gregory, and friends decided to pronounce themselves the Yippies. (The name came first, then the acronym that would satisfy literal-minded reporters: Youth International Party.) [Todd Gitlin, "The Sixties," 1987, p.235]
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