From Readers Digest (They’re still around?):
If someone orders a frozen drink that’s annoying to make, I’ll say, “Oh, we’re out. Sorry!” when really I just don’t want to make it. But if you order water instead of another drink, suddenly we do have what you originally wanted because I don’t want to lose your drink on the bill.
If you make a big fuss about sending your soup back because it’s not hot enough, we like to take your spoon and run it under really hot water, so when you put the hot spoon in your mouth, you’re going to get the impression—often the very painful impression—that your soup is indeed hot.