In Japan there are numerous festivals known as Hadaka Matsuri that involve male participants wearing nothing but loincloths performing various feats or just jostling and fighting with each other.
The Yanaizu Hadaka Mairi is held every January 7th at Enzou temple in Fukushima. A large group of men climb a thick rope inside the temple to try to reach the ceiling. It is competitive and the first men to the top will have the best luck in the coming year.
These festivals can get very rough and fist fights might even ensue.
The Kompira Hadaka Mairi is held on January 10th (lunar calandar) at Kompira-jinja in Nishimura in Akita. Semi-naked male participants first purify themselves in the cold river and then offer gifts to the shrine. It seems that most of these naked festivals are held in the winter as a challenge to participants.
The Tokimata no Hadaka Matsuri is held in early February every year. The event is always held on a Sunday but the method for calculating the date seems a little complex. It is the nearest Sunday to the first Horse Day in February (lunar calandar). In this festival, half naked participants parade around with a heavy horse statue (a kind of mikoshi) and jump into the half frozen waters of a river with it. It is held at Choukoku temple in Iida, Nagano.
Hadaka Matsuri are real spectacles and some of them occasionally make the international press.