http://goasia.about.com/od/countriesaz/p/naked_men_japan.htm

http://www.optic.or.jp/saidaijicci/pho_eyo_01.jpg
Japanese guys going naked!

The Attraction: The festival is bizarre. There is an erotic element (after all, Shintoism is a religion of fertility); thousands of men clad only in fundoshi (a type of loincloth) and sandals. One source describes it as "homoerotic." The festival is also brutal. Steam rises off of the skin of participants as they wash in freezing water to "purify" themselves and then stand stand, jog, or hop around on one of Japan's coldest nights. The festival can be bloody as well as brutal. Fighting is common among the participants. Japanese beer and rice wine both flow freely and there is party atmosphere complete with fireworks.
The History: Most sources date the ceremony back to the 1500's. During the Eisho Era of the early 1500's priests at the temple distributed amulets thought to bring good luck. The amulets became popular and the priests began tossing them into the temple crowd at the Lunar New Year's celebration. Originally the amulets were paper. Over time they evolved into decorated wooden sticks about eight inches long. The temple, Saidaiji Kannon'in Buddhist Temple, was established in 765 A.D.
The Environment: Saidaiji is in Okayama prefecture and the Kannon'in Temple there is set against the backdrop of the Yoshii River. Winter in the region can be harsh. Temperatures below freezing are not at all uncommon at night.

and yadda yadda yadda... see linky for more....

The Atmosphere: It's difficult to do justice to the unique feel of this festival coming at about the time of the Lunar New Year. The alcohol and fireworks make it feel a little like an independence day celebration of some sort. The competitive violence and police presence makes it seem like something between a riot and a rugby match.
The Activities: Three different events for school children get stretched out over a few hours starting at 6 pm. Men from their early 20's to late 40's start going into a tent on the temple grounds around 9 pm where an attendant helps them put on their fundoshi (loincloth). Participants can get free alcohol in the tent. The nearly naked participants come out into the night air and begin jogging around the compound and participate in ritual washings in preparation for the main event. At 11 pm participants go into the crowded temple area and wait for an hour. At midnight the shingi are dropped into the crowd and the struggle begins.
The Participants: Technically, any adult can participate in the event. Evidently a woman never has. A number of Gaijin (foreigners) take part every year. It is unclear whether there is an age limit. One source says participants must be between 23 and 43 years old. Many of the men who participate are pressured into taking part as members of work place teams. In any given year there can be as few as 3,000 participants or as many as 10,000 participants. Spectators number upward to about 30,000.
Health and Safety: Hypothermia is a serious issue and numerous cases of it get treated at the event's first aid tents each year. More serious health concerns arise from the competition itself, however, since violence in the competition area seems not to be prosecuted unless it results in a death. In other words, men who don a fundoshi and enter the competition may have the holy snot literally kicked and/or beaten out of them. Gaijin (foreigners) seem more prone to attack, and seem to fair worse when one occurs. The police may rescue you, but your attackers will simply return to the competition (even if they assault the police).
Time: Third Saturday of February. There are events in the early evening for younger boys, but the main event starts at about 11pm. The shingi are dropped into the crowd and the struggle starts at midnight.
Cost: Entrance to the event as either a spectator or participant is free. There are some raised seating areas available for a fee if you want to be above the crowd.
Brave Men Wrestling Naked for Good Luck: It looks as bizarre as it sounds: seven or eight thousand men standing together nearly naked, dressed much like sumo wrestlers, steam rising from their wet bodies in the winter chill, their breath coagulating in the air in front of them like wild stallions on the tundra, and frostbite beginning to show on their bare buttocks as they push and shove for what they perceive to be a more advantageous position on the temple's main floor. All supposedly for a year's worth of good luck.

Many of the men have imbibed enough alcohol to cloud their judgment or give them an unrealistic view of their own physical prowess. You can feel the excitement and smell the male hormones.

They are asked to spend an hour waiting together - cold, nearly naked, cramped together in close quarters. It is no wonder that fights break out. And as the crowd watches, small groups of participants single out those in the game whose behavior has been particularly offensive and that unfortunate soul gets thrashed and beaten to the edge of the crowd before being evicted from the game - even before it starts.

At midnight the lights go out briefly and a priest tosses two sacred sticks, or shingi, into the crowd of impatient, intoxicated, belligerent participants. The battle begins. The lights come back on. The crowd watches. And eventually someone manages to thrust each of the shingi into a raised box of rice. The winner(s) get a cash prize - and a year's worth of good luck...

A bunch of nekkid men with eight inch wooden sticks...interesting -lemme grab a camera!