John and Jake went into a diner that looked as though it had seen better days. As they slid in to a booth, John wiped some crumbs from the seat. Then he took a napkin and wiped some mustard from the table. The waitress, in a dirty uniform, came over and asked if they wanted some menus.

"No thanks," said John, "I'll just have a cup of black coffee."

"I'll have black coffee, too," Jake said. "And please make sure the cup is clean."

The waitress shot him a nasty look. She turned and marched off in to the kitchen. Two minutes later, she was back.

"Two cups of black coffee," she announced. "Which one of you wanted the clean cup?"