1. Pushing people to contribute to an expensive gift for the boss. Gifts in a workplace should flow down, not up, but too many stories abound about employees being pressured to contribute money for gifts for their managers. Often these gifts are pricey ones – more extravagant than what the employees will buy for those closer to them – which is especially inappropriate. Workers shouldn't have to return their hard-earned money to the people who hired them.
2. Insisting on knowing why your co-worker isn't bringing a date to the holiday party. Your co-worker might be going through a divorce, a break-up, dating someone they don't think would enjoy attending someone else's office function, dating someone they're not serious enough about to bring along or not dating anyone at all. Regardless of the reason, it's none of your business, and you will make people uncomfortable if you demand to know why they're coming solo.
3. Claiming all the good vacation days for next year before anyone else does. If your office approves vacation days on a first-come, first-served basis, you might technically have the right to claim all the most popular holidays in the upcoming year before anyone else does. But you can be sure that your co-workers notice that you do this and resent you for it.
4. Giving a gift of no value in the office gift exchange when everyone else is exchanging real gifts. You shouldn't feel obligated to participate in an office gift exchange, but if you choose to, you should honor its customs. If everyone else is exchanging nice trinkets, you should not give a gag gift like a bag of coal or a box of sawdust (real gifts people have reported receiving). You might think it's funny, but you risk hurting the recipient's feelings or making them resent the work they put into picking out something more thoughtful.
5. Giving an extravagant gift that's well over the dollar limit set in your office. If your office sets a dollar limit on gifts, it's there for a reason. If you significantly exceed it – for instance, giving a cashmere sweater or an iPod when the gift limit was $15 – you'll make everyone else participating feel awkward.
6. Pressuring people who aren't merry enough for you. Bugging people about why they're not going to the holiday party or participating in Secret Santa – or worse, signing them up for Secret Santa without their permission – is a good way to alienate co-workers. Keep in mind that for every person who enjoys holiday rituals at work, there's at least one more who doesn't, especially at a time of year when budgets are often stretched thin and people don't want the office to become another holiday expense.
7. Offending people of different religions than you. Not everyone celebrates the same holidays and even those who do might not celebrate them in the same ways. Don't push people to celebrate in ways they're not comfortable with.
8. Getting drunk at the office holiday party. While it might look an awful lot like a social function, the reality is that the office holiday party is still a business event. You're there to mingle with co-workers and higher-ups, not to get drunk or otherwise act in a way that calls embarrassing attention to yourself. Raise your visibility by being smart and engaging, not by being the person who slurs Christmas songs from the top of a table or passes out in the bathroom.
Alison Green writes the popular Ask a Manager blog, where she dispenses advice on career, job search, and management issues. She's also the co-author of Managing to Change the World: The Nonprofit Manager's Guide to Getting Results, and former chief of staff of a successful nonprofit organization, where she oversaw day-to-day staff management, hiring, firing, and employee development.