HotToddy saidThis hanky code fascinates me. 1) How the hell are you supposed to remember all that!? 2) Was this for a specialized setting (ie in a gay bar) or would you wear them anywhere to get picked up?
Most of the time it was just a few basic colors, to say if you were a top or bottom, or into anything more kinky. It began in the pre-Stonewall gay clubs when even there you had to be discreet, and for years afterwards as anti-gay laws only gradually disappeared.
Gays had their clubs, like Stonewall, but they were technically illegal in most US jurisdictions. Subject to frequent police raids, and infiltrated with undercover cops, you had to be careful how you communicated your interests to other guys. Speaking them to a plainclothes detective would get you arrested, even in a so-called gay club. So the hanky code developed.
My partner tells me about the clubs in Boston, where most gay guys went with a woman, the original fag hags, who were used as decoys. You danced with other guys, until the alarm was given that the police were coming in. Then you all grabbed a woman on the dance floor, a bizarre form of musical chairs, and if you lacked a woman, you quickly tried to find a table to sit down.
The police also knew the game, and would interrogate the men, seeing if they really knew the name of the woman with whom they were dancing or sitting. Another thing the police did was underwear checks, of any drag performers. It was legal for men to wear women's outer clothing as part of a stage costume, but you still had to wear men's shorts underneath. Women's undergarments were illegal, even bras in some locales.
The police checked underwear both in the clubs and on the public streets outside. They also made you confirm that you were a scheduled act. If not, you were arrested. Likewise if you wore makeup not part of a stage performance.
So the need for gays to communicate surreptitiously even inside nominally gay clubs created various forms of non-verbal communication. Today in the US these are not really needed, unless I suppose in a straight place, and becoming obsolete.