{v. phr.} To perform an act of kindness, friendship, or help to another person, unselfishly, without expectation of reward. * /"I'll be happy to help you any time you need it," John said. "After all you have done me so many good turns."/
DO ONE A GOOD TURN
Meaning of DO ONE A GOOD TURN in English
Dictionary of English idioms . Словарь английских идиом. 2012