Usually getting a baby to stop crying is the hard part of any parents' day, but during the Nai Sumo Baby Crying Festival the goal is to get the wee babes to start and keep crying to get rid of demons.
The traditional festival takes place at the Sensoji Temple in Tokyo each year, pairing up tiny little babies a sumo wrestler who will then try to get the little guy to cry. The origins of the bizarre practice date back hundreds years to a simple proverb that state, "Naku ko wa sodatsu," or "Crying babies grow fat." The other reason behind the festival, is the belief that somehow the piercing wails work to drive off nearby demons that would otherwise bring you to harm. While neither of these claims are proven to work, that hasn't stopped people form making their children cry in public.
During the ceremonies, sumo wrestlers take the stage and hold up the participating babies (their parents actually brought them to this), and try to get them to start bellowing. Among the techniques used to make the babies unhappy include putting on a scary mask to freak them out and the old stand by of just yelling, "CRY! CRY! CRY!" into their little faces. But it's all worth it, because if they are the best cryer, they are ensured a long, healthy life.
For all the seeming cruelty of the event, it actually has a fun, jokey air as the adults seem to realize that intentionally getting kids to cry is a little goofy. The kids do't seem to be in on the joke.