You're sitting around a table with some of your co-workers, what do you do?
Shift your eyes back and forth while they converse, of course.
Insert laughter when acceptable.
Say a word or two when spoke to.
Pretend you're listening to the boys discussing cars.
Stare off into space...but shift back to pretending to be interested in other peoples conversations about people you don't know so you don't come off as a snob.
Oh look, you've gone through 2 iced teas!
Dinner is over, everyone is shifting awkwardly in their seats, not wanting to be the first to make a move.
You decide to accept the challenge and stand up, everyone follows.
Conclusion: say no to staff dinners. On the plus side I got free food. Free is good, always.