DEAR MISS MANNERS: Several times when I have invited and offered to treat someone at a restaurant, my guest has added a to-go order.

For instance, mid-celebration, a birthday celebrant received a whiny hungry call from her husband, and zap, my bill increased by $100. On another occasion, a client ordered a to-go dessert and made a faint gesture to pay — no reaching for his wallet or asking the waiter for separate checks. Of course I ate the bill. Another was a relative, and a known moocher. I should have been prepared for that one.

It’s hard to go from being generous to a hard stop. Do I just stop inviting anyone to restaurants? Is there a witty thing to say that doesn’t come off as me being a tightwad?

GENTLE READER: The first time Miss Manners heard about someone doing such a thing, she was astonished. Would anyone really have the gumption to con a generous friend like that?

Well, yes. She has now received a number of such letters reporting this petty crime — several people have done this to you, personally — and in each case, the host is embarrassed into sponsoring the fraud.

Well, don’t be. The thing to say when it happens is, “I believe this part of the order is yours. How do you want to pay for it?”

Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, [email protected]; or through postal mail to Miss Manners, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.