Did he just drink from my water glass? Did she just eat my bread?

Prevent tabletop turf wars by memorizing two simple rules: Your glasses are on the right; your bread plate is on the left. (If you forget, think BMW, for “bread, meal, water”—the left-to-right order of items when you’re seated at your place.) “If the poor person next to you took your bread, don’t make him feel ill at ease,” says Dupree. She recommends gently asking the unwitting thief, “I might be mistaken, but isn’t that mine?” Post advises claiming the bread plate on your right (as the original perpetrator did) and hoping that the whole table plays along. Cynthia Rowley, a fashion designer and the coauthor, with Ilene Rosenzweig, of Swell: A Girl’s Guide to the Good Life (www.amazon.com, $24), suggests flirting to make light of the situation: “Try interlocking arms and playfully telling the person you’re happy to share your bread.” Of course, at a restaurant, you can just ask the server to bring you another plate, notes Monique McCambridge, a former waitress and special-events manager at Jardinière, in San Francisco.