We don’t quite know who invented the high five—but we can pinpoint the moment it became inextricably linked with sports, which the short documentary The High Five explores below.

On October 2, 1977, Los Angeles Dodgers leftfielder Dusty Baker scored his 30th home run, making the team the first in history to have four players—Baker, Ron Cey, Steve Garvey, and Reggie Smith—with at least 30 homers under each of their belts. Fellow outfielder Glenn Burke was so overwhelmed with joy and pride, he raised his arm and slapped his flat palm against the victorious athlete’s own palm. The moment transformed Baker and Burke into legends.

Sadly, the latter player faced hard times ahead: Burke was gay, and it’s believed that his sexuality prompted team officials to trade him to the Oakland A's the following year. In Oakland, Burke clashed with team manager Billy Martin, then retired early from baseball. Today, Burke is remembered for his charisma and talent—and for transforming a simple gesture into a universal symbol. “To think his energy and personality was the origin of that, that’s a pretty good legacy,” sportswriter Lyle Spencer says in the film.