1. When your boss or CO (commanding officer in military terms) makes it a requirement to show up to a pick-nic, BBQ, or some other stupid crap in order to build "team spirit" or "esprit de corp."
2. Your boss has no friends of his/her own, and decides that all of his/her subordinates should show up to one of his/her lame functions.
3. The Colonel or Sergeant Major have no friends and everyone hates them. Therefore, their subordinates are required to put on their 'Class A' or 'Dress Blue' uniforms and listen to some old guys make drunken, teary-eyed toasts to their first pair of jump boots.
Platoon Sergeant: "Tomorrow is the brigade ball. Everyone is required to attend.
Private: "Is this one of those MANDITORY FUN DAY's, Sergeant?