Mister Fog

Pulled over for exceeding the speed limit the police officer came over to speak to me. I told the officer that I hadn't realised I was speeding but that the road was clear and visibility was good.

"Well sir, how would you have reacted if Mister Fog had suddenly appeared?" he enquired.

Annoyed at his patronising manner, I facetiously replied, "I suppose I would've applied Mr. Brake and summoned up Mr. and Mrs. Headlight!"

Smiling, the officer carefully repeated what he had said,

Spoiler:

"How would you have reacted if mist.... or... fog had suddenly appeared?"

That sounds like a Lee Mack gag?