Koreans have been drinking maple sap since the ninth century. They tap maple trees know as the gorosoe, or "tree good for the bones." The right way to drink gorosoe is to drink 5 gallons at once.
According to one popular legent, Doseon, a ninth-century Buddhist monk, achieved enlightenment after months of meditating cross-legged under a maple tree. When he finally tried to get up, his stiffened legs would not work. The sap from the tree fixed the problem. Hence the name's meaning it is good for the bones.