The handkerchief code, or hanky code, is a way to indicate what forms of BDSM play you’re into. It originated in the gay leather scene, and has since been widely adopted in the kink and queer communities.
More About Handkerchief Codes
Using the hanky code is most common at public events. It helps someone spot people with compatible interests at a glance. It is especially useful for casual play.
The handkerchief is usually tucked into a back pocket, but it could also be tied on a wrist or ankle, pinned to a backpack, or even worn in the hair.
A hanky on the left side indicates that you’re a top for the given activity, and a hanky on the right side indicates you’re a bottom.
The color of the handkerchief indicates what you’re into. Black indicates BDSM, red indicates fisting, grey indicates bondage, and so on.
The hanky code is also called “flagging” as in “flagging as a bondage top.”