A businessman is hurrying home on the motorway after a hard days work when he is stopped by a policeman.

"Do you know you were driving 30 mph over the limit?" asks the policeman.

"Eh, actually no, officer, it's a big car and it just sort of coasts along... you know."

"And what were you planning on doing if you met Mr Fog?" demands the policeman.

"Well," says the businessman, thinking it best to play along, "I suppose I'd ease off on Mr Accelerator, and switch on Mr Headlights and Mr Windscreen wipers."

The policeman leans in the window and eyeballs the businessman. "I asked you what you were planning on doing if you met MIST OR FOG!"

And threw the book at him.