It's rude to expect someone to buy something for you.
Mike and Gary are going on a road trip for the day.
Mike wants to spend as little money as possible.
Mike packs his own lunch and looks up a couple of nature activites that are free of charge.
Mike leaves his wallet home assuming that Gary will cover him.
Mike and Gary have a great day trip and Mike spends a minimal amount of money.
Gary is fed up with Mike and refuses to give him money leaving Mike to go hungry for the day.