Ducking the Fog is a spoonerism, or swapping the first two letters in two words. It is a more polite version of the phrase 'Fucking the Dog'. The meaning of both is 'doing nothing.'
Example: In response to the question "What are you doing tonight?" you might answer, "The usual, fucking the dog." Or "Ducking the fog, man."
by SteveW1 October 11, 2014