This picture taken on February 23, 2014 shows participants wearing dresses running half-naked in the annual 3.5 km Undie Run held in the Olympic Forest Park smog-covered Beijing. Some 200 participants took part in this event, many of them with gas masks, as dangerous smog blighted swathes of northern China in recent days. (Photo by AFP Photo/STR)

A Naga sadhu, or naked Hindu holy man, pauses inside a tent during Kumbh Mela, or Pitcher festival, at Trimbakeshwar, India, Thursday, August 27, 2015. Hindus believe taking a dip in the waters of a holy river during the festival will cleanse them of their sins. The festival is held four times every 12 years. (Photo by Bernat Armangue/AP Photo)

Indian Naga Sadhus, or naked holy men, participate in a procession before taking a “shahi snans”, or holy bath, at the Sangam river, the confluence of three of the holiest rivers in Hindu mythology, the Ganga, the Yamuna and the Saraswati, during Kumbh Mela festival in Allahabad, Uttar Pradesh, India, 15 January 2019. The Hindu festival is one of the biggest in India and will be held from 15 January to 04 March 2019 in Allahabad. (Photo by Rajat Gupta/EPA/EFE)

An Indian sadhu (Hindu holy man) sits on the banks of Sangam – the confluence of the Ganges, Yamuna and mythical Saraswati rivers – on the auspicious bathing day of 'Maghi Purnima' during the Kumbh Mela festival in Allahabad on February 19, 2019. Millions of Hindu pilgrims took the plunge in holy rivers on the most auspicious bathing days of the Kumbh Mela festival, led by naked, ash-smeared holy men and accompanied by chants from Hindu holy texts. (Photo by Sanjay Kanojia/AFP Photo)

A boy plays on the glass at Thailand's first skywalk in Bangkok, Thailand on November 18, 2018. (Photo by Soe Zeya Tun/Reuters)

Boys play with a drainage culvert used for flood control in Las Pinas, Metro Manila February 28, 2016. (Photo by Erik De Castro/Reuters)

A local boy plays football on Iracema Beach on June 11, 2014 in Fortaleza, Brazil. (Photo by Robert Cianflone/Getty Images)

Men pull as a boy stands on a soap cutter in a soap factory in Idlib province, Syria January 30, 2016. (Photo by Ammar Abdullah/Reuters)