Young Red Dzao hill tribe used to come to Sapa to sing songs to the opposite sex. Girls sang the songs hidden in the dark, when a boy found them, and if they matched together, they disappeared into the forest for three days. Some of them got married after that.
While Dao women are indeed highly industrious, the men, it seems, prefer to spend most of their time drinking, smoking opium or sleeping, only occasionally slapping the rump of a lethargic bovine moving more slowly than they are. Few of their songs, though, are about drinking, smoking opium, sleeping or slapping rumps.
Currently you may spot some young locals singing in the dark, but they are not looking for a partner, they are looking for you. They will sing a song, and ask for a tip afterwards.