Stack Exchange Winter Bash 2015 is coming soon! Are we in??
For those who are new to the Stack Exchange network, Winter Bash is an annual light-hearted event where users can earn virtual "hats" by doing certain things on an SE site within the Winter Bash time frame -- these virtual "hats" that you earn can be "worn" as adornments on your SE avatar either on a particular site (e.g., Coffee) or network-wide (i.e., all of Stack Exchange).
The conditions for earning certain hats are "public" -- well-known to all; other hats are "secret" -- you need to figure out what to do to earn the hat. Some public hats might be... ask a well-received question, improve a question, submit an accepted edit, perform tasks in the review queue, etc. Some non-public hats in the past have been... contribute on a particular day, upvote and comment/improve on a first-question from a new user, etc.
Winter bash can be fun and users will sometimes get hats just by participating normally. Any user can opt-out of the Winter Bash (once it starts, any user can click a link like "no hats for me, thanks"); no hats will be earned nor viewed.
Once Winter Bash 2015 begins (14 December), stats can be viewed at http://winterbash2015.stackexchange.com/ . Previous years can be viewed at the respective years, or by redirects from previous years -- e.g., http://winterbash2014.stackexchange.com/ directed to for 2014 and blog posts like this one with more info about secret hats!
An entire site could also opt out of Winter Bash. Are we in, Coffee?