If for any reason a guest has to leave the table during a meal, he or she should ask the hostess, "Would you please excuse me for a minute?" When the meal is finished, the guests put their napkins on the table and rise. Guests do not fold their napkins in the original folds unless they are house guests and intend to stay for more than one meal. Following dinner, guests usually stay for two or three hours, but the thoughtful person is careful not to overstay his or her welcome. The host and hostess may urge a guest to stay longer in order to be polite, but most dinner parties break up at about 11 o'clock. As the guests leave, it is the custom to thank the hostess for a very pleasant evening. One may say anything that expresses appreciation. Common expressions are: "Good-bye. It was so nice of you to have me," or "Good-bye. It's been a thoroughly enjoyable evening," or "Thank you. I've had a very nice time." For larger favors than a dinner party, such as an overnight or weekend visit, it is customary to send a thank-you note.