Naked Sadhu wearing a strange wooden apparatus that seems to be some sort of underwear or chastity belt, at the Kumbh Mela 2013 Hindu festival near Allahabad (India).
See another photo.
I saw a group of naked Sadhu (Hindu holy men), all wearing this thing when they went to take the Holy Dip in the Ganges river.
Here is some info I found about those devices:
As an aid to mental control of sexuality, physical restraint must sometimes be employed and one method is the continuous wearing of 'chastity belts'.
It is a rather 'recent' austerity, not more than 300 years old, and it is only done by Vaishnavas of the Nimbarki Sampradaya. This austerity, like most, is usually undertaken for a minimum of twelve years.
This man is a Kathia baba. This wooden arbandh, with its wooden langoti attached, may quite rightly be called a 'chastity-belt'; only this one is self-imposed.
The langoti can be unhooked for cleaning, but the arbandh of course stays on all the time.
Kumbh Mela is the largest festival on Earth, taking place once every 12 years, with more than 50 million Hindu pilgrims gathering to pray and bathe in the holy Ganges river.