April 2, 1974.
It was the night of the 46th Annual Academy Awards, and the time had come to announce the nominations for Best Picture. David Niven took the stage at the Dorothy Chandler Pavillion to introduce Elizabeth Taylor, that year's presenter for the Best Picture Oscar.
It is at this point that Robert Opel, a 33-year-old photographer and art gallery owner, enters the scene. Opel had obtained a press pass, was waiting in the wings, and right when Niven was about to bring on Ms. Taylor, he discarded his clothing and streaked across the stage, flashing (among other things) the peace sign. His rationale, he told the L.A. Times, was that "it might be an educative thing to do. You know, people shouldn't be ashamed of being nude in public. Besides -- it's a hell of a way to launch a career."
David Niven handled the situation remarkably well, delivering in a deadpan tone, "Just think: the only laugh that man will probably ever get is for stripping and showing off his shortcomings." When Elizabeth Taylor took the stage, she told the audience, "That's a pretty hard act to follow. I'm nervous -- that really upset me. I think I'm jealous!"
This was all before the Academy had instituted a broadcast delay to keep this sort of thing from being aired (the delay was put into action the following year). The streak was seen by millions of TV viewers across the globe, and Opel became something of a cult hero. He later used this notoriety to promote gay artists in his gallery.
Pop/novelty artist Ray Stevens capitalized on Opel's antics as well. After watching the Oscars and reading an article about the streaking craze (this was 1974 - streaking was all the rage), Stevens thought it made for a great song idea, and recorded "The Streak." It wound up being one of 30-40 "streaking" records that year, and wound up at the top of the pack, making it to the #1 spot on Billboard's Top 100 in just five weeks.
Five years later, in 1979, Opel was shot to death during a robbery at his apartment (which doubled as his erotic gay art gallery). That's the story as most people know it, anyway; the police maintain that he was a drug dealer and suspect that the death was a deal gone wrong.
Incidentally, Best Picture honors in 1974 were bestowed upon The Sting, starring Robert Redford and Paul Newman.