You show up at the door in your pink bunny outfit and find that — oh, didn't you hear? — it's not a costume party after all. Or you wear cutoffs to a barbecue that turns out to be a black-tie affair. There's just one thing to do:

Go with it. First, be sure you're even making a bad impression. Ann Demarais, a coauthor of First Impressions: What You Don't Know About How Others See You (Bantam, $10, www.amazon.com), points out something called the spotlight illusion, in which a person's natural egocentrism leads him to think others are paying attention to him when they're not. In fact, most guests are probably more concerned with their own appearance than with yours. And even if you do stick out, "focusing on it will only make you more self-absorbed and less able to connect with others," says Demarais. Rather than trying to hide, act confident and show that you see the humor in the situation. "Acting as if everything's OK takes a certain amount of courage, and people respect that," says Dickinson. The people who make the best impressions are those who are comfortable in their own skin — even when it happens to be dressed, however inappropriately, in a bunny suit.