It's good to reimburse people.
Mark owes Charlie $20 for dinner.
Mark wants to save money for a new video game.
Mark pays Charlie the money he owes him and works extra hours for money to buy the video game.
Mark avoids Charlie in the future and buys a video game with the money he owes Charlie.
Charlie is happy that Mark repaid him.
Charlie is offended that Mark won't pay him and decides to not be friends with Mark anymore.