My Corporations professor discussed agency on the first day of class. He proposed a hypothetical where his assistant (he works at a firm) bought lunch for a meeting and paid with a firm credit card that she'd been told specifically never to use for that purpose. The firm eats the food and then refuses to pay the bill. The question was whether his assistant was an agent of the firm such that the firm could be held liable for the lunch.
My prof asked, "So, will I have to pay for the lunch?" He let us marinate on it a moment and then said with a smirk, "You know I’m gonna have to. Because there’s no such thing as a free lunch."