Stack Exchange is running a special event, site wide, called Hat Dash. The question is, Do you want to "Opt In"?
The link below is the community blog post announcing it last year on the gaming site Arqade.SE, but here are some general bits of informaton...
- The event will run from 19 December 2012 to 4 January 2013.
- Individual users who don’t want to participate, don’t want to see hats, and/or are generally anti-hat will have an "I hate hats" option available.
- Users will be able to see their entire hat collection on http://winterba.sh. That site will also have a landing page, explaining the rules and other details of the event.
If you'd like for Poker.SE to get involved then reply in the thread and the mods will do the rest.
Extra Info: Hat Dash Info from 2011