be a sport

be a sport

1. To be helpful and amiable. In this usage, the phrase usually precedes a request. Be a sport and get me another drink, will you?
2. To be good-natured or amiable despite unpleasant circumstances. In this usage, "good" is usually used between "a" and "sport." I know you're disappointed to have lost the game, but try to be a good sport, OK?
See also: sport
Farlex Dictionary of Idioms.

be a (good) ˈsport

(informal) be generous, cheerful and pleasant, especially in a difficult situation: She’s a good sport. Go on, be a sport (= used when asking somebody to do something for you).
See also: sport
Farlex Partner Idioms Dictionary
See also:
  • good sport
  • able to take a joke
  • take a joke
  • good-natured
  • grin and bear it
  • twinkly-eyed
  • because of
  • regular guy
  • guess what
  • Guess what!