I think a good Christmas event would be a present hunt. The moderators would hide an amount of presents around spawn, and players would click them to find them. Each present would have goodies in it. And a prize could be given to each player who finds all of the presents.
I like this idea though, I believe this is how the Easter event is, not sure if they would make both events similar in this way. Last year for christmas there was a big event so I'd imagine thats probably coming back soonish or closer to christmas (hopefully) though maybe something like a world wide present hunt? Like chests randomly generated throughout the world and cords are posted on disc for people to find
