Post Christmas Depression 

It's when you're sad because Christmas has passed, and you know that you're going to have to wait almost a year before the next time you get free stuff other than your birthday.

Bro 1: "You don't look so hot, are you okay?"
Bro 2: "Yeah, just post Christmas depression is all."
Bro 1: "Oh yeah, now that you've reminded me, I'm also suffering from PCD..."

Post Christmas Depression by Clemens Hemmingway December 5, 2010

Post-Christmas Depression 

That period of time, usually following New Year's, when you must take down all Christmas decorations and as a result, your house feels cold and naked.

John: Aw man... that spot by the fireplace where the Christmas tree used to stand feels so empty now.
Bob: Yeah, you're suffering from Post-Christmas depression. We all get it.

Post-Christmas Depression by TheSantaClaus December 30, 2011

Post Christmas Depression (PCD) 

Usually occurring on or after December 26th, when all of the Christmas festivities come to an end and you have nothing to look forward to except for a long, cold, boring ass winter.

Tom suffers from Post Christmas Depression (PCD) every year right from the time when he opens his last present on Christmas Morning up until Black Friday of the next year.

Post Christmas Depression (PCD) by Taylor the Terrible December 24, 2008