Mistaking Plumpness for Pregnancy

Real-Life Example: "This happened to a friend of mine," says author Peggy Post. "She ran into a business associate she hadn't seen in a while at a meeting and said, 'It's so nice to see you! When are you due?' To which the woman replied, 'I had my baby months ago.' My friend was so embarrassed, and it was extremely awkward between them from then on."

How to Remove Your Foot: "In this instance, groveling is in order," says author Caroline Tiger. "Apologize profusely, say how stupid you feel, then move on. Don't dwell on it or make up excuses." If the person is a friend or a colleague whom you see often, Post suggests writing a note to further smooth things over. "That being said, it's awkward to write a note, too," she says. "Just keep it simple: 'I can't believe I did that. Please accept my apologies.'"

In the Future: If you aren't 100 percent sure, don't say anything. "I did this once and learned my lesson," says Charlotte Ford, the author of 21st-Century Etiquette ($14, www.amazon.com). "Now I ask somebody else first if the person is pregnant or not. And if the other person isn't sure, then I keep my mouth shut." Chances are, a woman who's expecting will bring up the topic herself.