If you do partake of spirits, limit yourself to one drink, and then shift to soda or water.  Over-indulgence may elevate you to "life of the party" status, but it can spell the "death of your career."  Back in the office, as opportunities arise for someone to represent your organization at important business functions, it won't be you.  You'll be relegated to winter never land.

 
Give Unto Others As You Would Have Them Give Unto You
 
Holiday parties inspire thoughtful gestures, like gift giving.  We've all been taught, "It's the thought that counts."  But at work, the gift speaks louder.  Use good judgment.  Don't bring a gift that you wouldn't be happy to receive yourself.  Funny gag gifts may spur short-term laughs, but they do little to enhance working relationships.  Don't allow others to become the butt of jokes.  Work egos can be very fragile.
 
Years ago I worked for an organization where we drew names out of a hat - and I drew the name of a guy named Fred who worked in Finance.  I knew very little about Fred's likes and interests -- and, as I quickly learned, neither did anyone else.  Playing it safe, I bought him a fruitcake.  When the time came to open it, Fred quickly misinterpreted my intentions and went berserk (thereby confirming the appropriateness of my gift, but setting the stage for a difficult relationship with the finance department over the next two years).
 
I suppose it's only fitting that the fruitcake be a perennial symbol of the season.  Much like the office holiday party, it's made up of a concoction of diverse and disparate elements, all thrown together and displayed as one cohesive unit.  Some of the ingredients may cause you to rejoice - others give reason to revolt.  But it endures long after the celebrations have ended.