Mate swapping, also called partner swapping or wife swapping, is the practice involving at least two couples who mutually agree to sexually exchange partners. This form of group sex may also include watching one’s partner having sex with someone else’s partner. Some of those who engage in this sexual practice say that it actually strengthens their marriage since they do not have to cheat and lie to their spouses. However, many of them also admitted that they experienced feelings of jealousy.
For instance, 10 couples go to a party and the male partners leave their car keys into a common bowl upon arriving. After the party, the female partners randomly pick keys and leave with the respective key owners.