"Yippie!" is incorrect should be replaced with "Yippee!"

*Yipee*: an exclamation of exultation and delight

*Yippie*: a member of the Youth International Party, Abbie Hoffman's band of counter-culture activists whose political statements were made through a series of notorious pranks and gestures, such as nominating a pig for the presidency of the United States, or filing applications for permits to levitate the Pentagon and blow up Detroit's General Motors building.