Mandatory Fun
A social event put on by an organization having some form of authority over event attendees where those attendees are generally confronted with the dilemma of attending the social event or facing some generally undesired consequence.
A: "Sorry, but I can't go to the beach with you this weekend. My employer wants us to attend this team-building retreat. If I don't go to the retreat, I'm required to show-up at my workstation and perform my duties."
B: "Oh, so they want you to have some mandatory fun, huh? It's okay!"