The Ambulance has got it's lights on 

Phrase used to convey to the current occupant of a toilet that the speaker on the wrong side of the door is in urgent need to use the faculties. Time is of the essence in order to avoid an unfortunate episode of self pollution of the under garments. To convey in the fullest sense that an emergency is in progress and the current occupant should get out of the way immediately .

For crying out loud Love, put your lippy on downstairs.....I'm stood out here and the ambulance has got it's lights on

The Ambulance has got it's lights on by Quantum Leaper June 5, 2010