There are numerous synonyms for the phrase "do a favor." Some examples of alternatives to the phrase could include: lend a hand, be of service, assist, aid, help out, perform a kindness, do someone a good turn, extend a favor, help someone out, and do someone a solid. Each of these phrases is slightly different, but all suggest an action taken to help someone else. Whether it's offering a helping hand or assisting with a task, doing a favor can make someone's day a little bit easier and make us feel better about ourselves.