The Nakizumo Crying Baby Festival is an annual ritual conducted in Shinto shrines across Japan. Sumo wrestlers carry babies into a dohyo (a sumo ring). Then priests put on bird demon masks and taunt the babies. The first baby in a pairing to cry wins. If both cry at the same time, the baby that cries the loudest is the winner.
Why do Japanese families do this? Traditionally, an innocent baby's cry is thought to ward off evil spirits. But the mothers interviewed for this video seem to be participating just to have a good time. They attended the festival in the city of Asakusa neighborhood of Tokyo, which is so popular that babies have to enter a lottery for the chance to participate.
-via Dave Barry