Prov. Do not trust an opponent who offers to do something nice for you. (A line from the story of the Trojan horse, as told in Vergil's Aeneid.)Jill: I can't believe Melanie brought me cookies today, when we've been fighting for weeks. Jane: Beware of Greeks bearing gifts. She probably has ulterior motives.When the rival company invited all his employees to a Christmas party, Tom's first impulse was to beware of Greeks bearing gifts, but then he upbraided himself for being paranoid.