Check out this video in which artist Hal Fischer discusses “gay signifiers” — namely keys, earrings and the hanky code — worn by gay men in 1970s San Francisco:
Hal Fischer’s work, Gay Semiotics, is a photographic study of visual coding among homosexual men.
You can see many of his photographs on the SFMOMA site.
Also visit gaysemiotics.com
Thanks to my buddy Grey for passing along this link!