Jon Mooallem traces the emergence of the gesture to Glenn Burke, a gay Dodgers player in 1977. Burke was abruptly traded to the Oakland A's in 1978, most likely because of his sexuality. But he found another home in San Francisco's gay community:
In the Castro, Burke's creation of the high five was part of this Herculean mystique. He would regularly sit on the hood of a car — whichever one happened to be parked in front of a gay bar called the Pendulum Club — flash his magnetic smile and high-five everyone who walked by. In 1982, Burke came out publicly in an Inside Sports magazine profile called "The Double Life of a Gay Dodger." The writer, a gay activist named Michael J. Smith, appropriated the high five as a defiant symbol of gay pride. Rising from the wreckage of Burke's aborted baseball career, Smith wrote, was "a legacy of two men's hands touching, high above their heads." …
Burke's friend Abdul-Jalil al-Hakim argues: "The high five liberated everybody. It gave you permission to enjoy your high points." And not just in sports but at your kid's spelling bee or your office after a killer PowerPoint presentation. In this interpretation, Burke didn't just add a bit of flair to baseball — he uncorked a repressed longing for personal expression and connection in all of American society.
The Dish 