You should always pay people back.
Jack's friend loaned him $10,000 in order to help him start a business, and he never gave it back.
Jack doesn't want his friend to hate him.
Jack gives his friend $12,000 as gratitude for helping him out.
Jack says that he donated the money to charity as a way of repayment.
Jack's friend feels closer to Jack and ends up with more money.
Jack's friend has financial problems and can't find anyone to help him.