The woman led me to the table and I asked politely if she had something else. “Hmmm,” she said, looking around. As she did, I reached into my pocket, pulled out two twenties and a ten, and moved them toward her hand. She continued—“I’m afraid there’s nothing”—when suddenly she felt the bills in her hand, claimed them, and announced cheerily: “Just a moment, I’ll go and check.”

Pocketful of Dough - Tips on Tipping