Christmas Party Rules You Should Not Break
Don't use the party as a time to gossip about co-workers or anyone else. Gossip is a bad thing anytime and I don't want to be anywhere near it. If someone does start to jibber-jabber about others, my advice is to move on. If you have to, change tables.
This can never be a good thing and can only do harm. Stay positive and friendly and use the time to try to learn things about co-workers that you don't already know. Engage in conversation with folks you rarely talk to. You never know what you'll learn.