I generally make it a rule not to attend such functions. Invariably, someone (or a group of someones) will be drunk. It is very difficult to view someone as a professional when you see them falling over, slurring their words, groping or being groped, etc.
I did go last year though, mostly due to the door prizes and the fact that I didn't have to pay to attend, as in years past. To be fair though, my coworkers did do a bit of arm twisting.
Ironic, when you consider some of them they really didn't treat me all that well during normal working hours (long story).
One day I hope to work for a company where I look forward to the annual Christmas party.
I lift things up and put them down.