There was a Roman priesthood whose job was to perform a specific dance and chant around sacred shields. Since this ritual was unchanged for centuries, later Romans had no idea what the ritual actually meant while still continuing the tradition.
If you’re flying aboard a spaceflight leaving from Baikonur Cosmodrome in Kazakhstan, you’ll be ordered to pee on the back-right tire of a bus. It’s tradition.
Liquindi, or Pygmy water drumming, is practiced by the Baka Forest People of central Africa. Tones are produced by trapping air in one’s hands and hitting the surface of the water, to create percussive musical rhythms.
A five year old boy was the victim of a ritual human sacrifice, in reaction to the most powerful earthquake recorded.