"Key party" is a term that originated in the 1970s and is associated with a certain type of gathering. The concept is thus:
Key parties were reportedly a component of the "swinging" or "wife-swapping" scene, which was part of the sexual revolution of the 1960s and 1970s. However, how prevalent these parties were is a topic of debate, and some believe key parties were more of an urban myth or an exaggeration of real parties that weren't as organized or formulaic.
Learn more: