McQuillan walked into a bar . . .

 . . . and ordered martini after martini,

each time removing the olives and placing them in a jar. When the jar was filled with olives and all the drinks consumed, he started to leave.

"S'cuse me," said a customer, who was puzzled over what McQuillan had done. "What was that all about?"

"Nothing," he replied, "my wife just sent me out for a jar of olives."