gift horse

Something obtained at no charge, but not without an ultimate cost. According to legend, it was Odysseus who devised the scheme of leaving a huge wooden horse in front of the gates of Troy, which the Greeks were unable to conquer (the losing side of a war traditionally left a gift for the victors). The Trojans watched the Greeks depart then dragged the horse inside their walls. Soldiers who had been hiding inside the horse surreptitiously opened the gates, the Greeks stole back inside the gates, and the rest is history. The cautionary expression “beware Greeks bearing gift” is based on the legend, as is the phrase “gift horse.” Stated another way, there ain't no free lunch