Hankerchief in back pocket question

[cman54]

Years ago I read about how when going out to a gay bar a guy can have a handkerchief hanging out of his back pants pocket. And the color of it tells what he is into. Does this still happen and what do they mean?

[Guest descartes70817]

https://unicornbooty.com/the-new-hanky-code-film-art-comedy-flagging/ says there's still a hanky code in use, but with so many hookup apps it seems a bit redundant.

[Leather69]

Having travelled a fair bit, attending events like Folsom (Berlin) etc .. the only ones that you tend to see these days are red (fisting) or occasionally yellow (piss). 

[nabatl]

I've also seen the color coded leather arm bands.