It is used to describe an instance in which something, unexpectedly, goes very well for an individual. It is from the Scottish Highland tradition of finding two stones in the ideal location from which to defecate. In the 1297 at Stirling Bridge, William Wallace, prior to his battle with the English, found two ideally aligned stones to sit on for clearing his bowels. He attributed the victory to those two stones. It has been used in Scottish lore and colloquialisms, to described unexpected good fortune.
by Wise Texan May 8, 2023