I N C I D E N T A L L Y:
This really occurred.
The head of the team in charge of maintenance in an airport hangar starts the foam gun used to wash the body of the planes. He receives an important phone call and must urgently return home.
He turns to his colleague, named Don, and says to him "Don. Turn it off!". With all the noise and general hullabaloo, the colleague understands only "Don't turn it off."
Please, please have a look on the ABTN web site. The event happened on a Friday evening. The photograph was taken the following Monday. http://www.abtn.co.uk