(ritualistic form of child abuse. But, you know, in a FUN way)
The 'Baby Sumo' festivals held annually in Japan do not, as it turns out, actually feature two infants being forced to fight while dressed in tiny sumo outfits. This is of course something of a disappointment yet as is so often the case with Japan the truth turns out to be gratifyingly demented in its own unique way.
The one-year-old contestants are dressed in traditional costume and placed opposite each other in a ring, held in the arms of their caring parents. At this point the shinto priest refereeing the "match" proceeds to try and make each baby cry, apparently mostly through a combination of sudden loud noises and, if that doesn't work, occasional poking. In a further pleasing inversion of expectations / common sense / general normality, the baby who cries first is declared the winner, crying being considered a sign of vitality and strength. This leads unscrupulous mothers to surreptitiously pull hair and pinch cheeks in attempts to grab glory for their offspring.
In a variant of this festival held in Asakusa, Tokyo, the entertainment quotient of the event - which I think you'll agree is already pretty high - is ratcheted up further by replacing the shinto priest referees with proper sumo wrestlers, who hold the babies above their heads and bellow terrifyingly into their faces.
I'm considering suggesting the introduction of this practice at my son's nursery, as I think it would help toughen the kids up, sharpen their competitive edge, and provide a fun and highly amusing day out for the parents. I'll let you know how that goes over.