Do dress tactfully.
First of all, remember that not every Halloween party is a costume party. Before you show up in your gorilla suit, ask someone. And second, an office Halloween party isn’t quite the same as the college Halloween parties you may have attended. Don’t forget that you're going to have to see these people every day after this. Playboy bunny and Tarzan costumes are probably better off at your personal parties, not your place of employment.
Don't be a party pooper.
If you know it’s going to be a costume party, dress up. If it embarrasses you to show your Halloween spirit, do something simple, even if it’s just a pair of Groucho Marx glasses. If you’re sure you're too old for costumes, you can at least withhold your snarky comments about the rest of your co-workers and appreciate that they enjoy the revels.
Do drink the punch.
If your boss or party planners were thoughtful enough to spike the punch or bring a few bottles of wine, that means you get to drink in front of your co-workers. If it’s a lunch-hour Halloween party, definitely stick to one glass. But if it isn’t, the fact that it’s provided for you means you don’t have to be ashamed to let your boss see you having a beer or two.
Don't bring your own drinks.
Having said that, let’s reiterate the fact that this is not the Halloween parties you went to in college. If you can’t hold your liquor, stick to the juice boxes. Even if you can, it’s probably not a good idea to pack your own schnapps and take sneaky shots in the bathroom. In this case, following the crowd is the way to go. The only flask you should bring is an empty one that’s part of your costume.
Do join in the revelry.
If whoever planned the party was thoughtful enough to come up with games, prizes, and contests, play along. Nobody actually likes them, but someone went to a lot of trouble to try to create a festive atmosphere. You aren’t too good to play Pin the Grin on the Pumpkin, and your co-workers are probably feeling just as ridiculous as you are.
Don't photocopy your butt.
Joining in the revelry doesn’t apply to the revels of a few people who did pack their own flask. Just because it’s a party and you’re off work, doesn’t mean that everyone in the room isn’t still judging you – or that they won’t remember absolutely every embarrassing thing you did when you show up to work on Monday. Even if you thought no one saw you in the copy room by yourself.
Do bring your plus one.
If the invitation says bring your significant other, bring your significant other. Co-workers are obscenely curious about the intimate lives of each other. But before your bring your husband and all six kids, check the PG rating on the party. The last thing you want everyone talking about at the water cooler is how your 3-year-old got into the spiked punch while your back was turned.
Don’t bring your entire extended family and all your college friends.
If the invitation says plus one, it really means plus one. Just because you feel like you’re underpaid and the company owes you, doesn’t mean you should get what you feel is coming to you by bringing your 10 closest friends or the homeless man you met on the street. Even if you hate your job, be respectful of your host. The office isn’t trying to throw a rave. They’re just trying to get everyone to bond.
Do enjoy yourself.
Maybe you have to behave professionally during office hours, but this is a chance to let your co-workers see the real you. You can let your hair down and take the stick out of your butt in front of everybody for once. Even if you’re a supervisor, you aren’t at the party to manage the business. So relax and have a good time. It’s a party, for Pete’s sake.
Don't stand in the corner.
If you’re going to the party because you know everyone expects you to, but you’re positive you won’t have fun and you don’t like any of your co-workers, you might as well not go. Make up an excuse, get magically sick at the end of the day, or just say that you’re busy. But if you’re going to rain on everyone else’s parade by standing in the corner making disparaging remarks about the secretary’s chicken costume, just stay home.