When both members of a married couple are simultaneously in a relationship with the same third party.
Girl: Can Scarlett Johansson be our Mutual Extramarital Relationship?
Guy: What?
Girl: You know, we both get to bang her if we get the chance.
Guy: What?
Girl: You know, we both get to bang her if we get the chance.
by RICH TEEJ October 6, 2011