In practicing various acts of kink, often discretion and enhanced communication techniques are required. As such a variety of secret codes are often put into place, though they are not universally followed or even understood throughout kink culture. Most of these codes are or were used to assist in cruising, a practice of seeking and signaling for casual partners for scenes and/or sex.
See Also Invisible Protocols
Munch codes often include being discreet with the public when discussing the munch or kink activities with or around vanilla folk. An example might be referring to the munch as "Computer club". Munches may also include certain other secret codes.
The handkerchief code (also known as the hanky code, the bandana code, and flagging) is a color-coded system, employed usually among the gay male casual-sex seekers or BDSM practitioners in the leather culture in the United States, Canada, and Europe, to indicate preferred sexual fetishes, what kind of sex they are seeking, and whether they are a top/dominant or bottom/submissive. The hanky code was widely used in the 1970s by gay and bisexual men, and grew from there to include all genders and orientations.
Today, wearing color-coded handkerchiefs (bandanas), usually in the back pocket or around the belt loop, is the manner in which communication of desires and fetishes is achieved, though acceptance and understanding of this practice may vary widely.
Wearing a handkerchief on the left side of the body typically indicates one is a "top" (one considered active in the practice of the fetish indicated by the color of the handkerchief), while wearing it on the right side of the body would indicate one is a "bottom". This left-right reality is taken from the earlier practice of tops wearing their keys on the left belt loop and bottoms on the right to indicate being a member of the leather subculture. In the past bandanas might be worn tied around the neck (with the knot positioned on either the left or right side); around the ankle (when wearing boots or when undressed); or on other parts of the body. There is no universally understood color code, and regional codes vary widely. There is general agreement upon the colors for more common practices, particularly those with an intuitive relation between the color and the practice, such as yellow for urolagnia; brown for coprophilia; and black for SM, but no absolute consensus for less common practices.
Key codes were the early predecessors of hanky codes where tops would wear their keys on the left belt loop and bottoms on the right to indicate being a member of the leather subculture. This practice is still sometimes used.