It's good to pay for your own things.
John is out at a restaurant having dinner and drinks with his friend Ron when the waiter brings the bill.
John wants the bill to be paid.
John opens his wallet and pays for his half of the food bill.
John says he forgot his wallet and insists that Ron pay for the entire bill.
John and Ron enjoy their evening out and maintain a strong relationship.
Ron feels irritated and upset with John's selfish behavior and it damages their relationship.