According to an author ('The Hipster's Handbook') just here
on the radio it is now currently Hip to use the word "Dec" in
conversation for the modern cool.
The spelling is mine, he probably used 'Deck' in his book
but my thinking is that without knowing the etymology, and
being from conversation, there is some (limited) chance
that Dec = DEC.
If you know this words origin give a shout.
John A.