Rating: You never want to meet Mr Skylight. That name over the Tannoy system is code aboard some cruise lines, for a medical emergency on the ship. Mr Mob is Mr Skylight's accident-prone friend: he signifies 'Man Overboard'. If you're on the Tube, hope that you never hear a message for Inspector Sands — that's the warning to staff that a fire has broken out. And if you're strolling around Edinburgh Zoo, especially if you're near the tiger enclosure, what you don't want to hear is 'Priority! Priority! Priority!' — a panicky code that means: 'One of our animals has escaped.'