For those that don't remember, users earned "hats" for their gravatars by completing certain tasks (analogous to badges). Certain actions would trigger the user receiving a hat, which their gravatar could then "wear". For example, editing a post would yield an editor-themed hat (fedora with pen) to the editor.
This event starts 12 December 2018 to 2 January 2019. Users will be able to see their entire hat collection on winterbash2018.stackexchange.com. That site will also have a landing page, explaining the rules and other details of the event.
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. And just like last time, at the end of the event, all hats will go back into storage.
Please comment, add answers below, and/or vote this question up or down (up/down votes on meta mean agree/disagree).