Fire drill
That unexpected black swan event that is certain to bugger up your weekend. It will start with clear and present danger, apprehended through the fog of war, confusion and miscommunication from panicked people in ops; it will gradually suck in more and more people across the organisation (legal, litigation, compliance, senior relationship management) and will eventually fizzle out as it becomes clear that neither the legal terms so patiently negotiated, firmwide policies copmpensdiously documented, or common sense has any preal prospect of overriding the dictates of keeping the client happy.