This porn video tag refers to a scene or event that involves gay sexual activity taking place at a party. In this context, "gay" refers to the sexual orientation of the participants, which is men having sex with other men. The term "sex party" suggests that there is more than one couple engaged in sexual activities, often in a social setting with multiple attendees. This tag is used to identify content intended for an adult audience who are specifically interested in watching male-on-male sexual interactions within a group or party setting.