The Hanky Code is also called flagging. It is a color-coded communication system adopted by queer men from the 1960s to the 1980s. It often involved placing a bandana or handkerchief in either pocket to convey a message. When the Hanky Code gained popularity, communication was limited to a few handkerchief or bandana colors. Red represented fisting, dark blue represented anal sex, light blue was used to signal oral sex, and grey was for bondage.
However, in the years that followed, the Hanky Code was expanded to more colors. It included a much more complex chart of over fifty handkerchief colors. For instance, Fushia handkerchiefs represented spanking, coral represented toe sucking, and beige represented rimming.
With each color-coded representation, the flaggers could place the handkerchief on the right or left pocket. Flagging in the left pocket meant the flagger was a top. The right pocket meant the flagger was a bottom or submissive player.