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This picture taken on February 24, 2013 shows paticipants taking part in the annual 3.5 km Undie Run held in the Olympic Forest Park in Beijing. Some 300 participants wanted to prove that Chinese can brave the cold just as well as any nationality and promote nationwide fitness. There were no winners, no trophies and no starting gun or finishing line. AFP PHOTOAFP/AFP/Getty Images

This picture taken on February 24, 2013 shows a man running with a doll during the annual 3.5 km Undie Run held in the Olympic Forest Park in Beijing. Some 300 participants wanted to prove that Chinese can brave the cold just as well as any nationality and promote nationwide fitness. There were no winners, no trophies and no starting gun or finishing line. AFP PHOTOAFP/AFP/Getty Images

This picture taken on February 24, 2013 shows paticipants taking part in the annual 3.5 km Undie Run held in the Olympic Forest Park in Beijing. Some 300 participants wanted to prove that Chinese can brave the cold just as well as any nationality and promote nationwide fitness. There were no winners, no trophies and no starting gun or finishing line. AFP PHOTOAFP/AFP/Getty Images

This picture taken on February 24, 2013 shows paticipants taking part in the annual 3.5 km Undie Run held in the Olympic Forest Park in Beijing. Some 300 participants wanted to prove that Chinese can brave the cold just as well as any nationality and promote nationwide fitness. There were no winners, no trophies and no starting gun or finishing line. AFP PHOTOAFP/AFP/Getty Images

People take part in the Naked Running competition at Olympic Park on February 24, 2013 in Beijing, China. 300 participants took part in the annual 3.5 km Undie Run, which was held in Beijing's Olympic Forest Park on Sunday. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images)

This picture taken on February 24, 2013 shows paticipants taking part in the annual 3.5 km Undie Run held in the Olympic Forest Park in Beijing. Some 300 participants wanted to prove that Chinese can brave the cold just as well as any nationality and promote nationwide fitness. There were no winners, no trophies and no starting gun or finishing line. AFP PHOTOAFP/AFP/Getty Images

This picture taken on February 24, 2013 shows a man wearing a gas mask during the annual 3.5 km Undie Run held in the Olympic Forest Park in Beijing. Some 300 participants wanted to prove that Chinese can brave the cold just as well as any nationality and promote nationwide fitness. There were no winners, no trophies and no starting gun or finishing line. AFP PHOTOAFP/AFP/Getty Images

People take part in the Naked Running competition at Olympic Park on February 24, 2013 in Beijing, China. 300 participants took part in the annual 3.5 km Undie Run, which was held in Beijing's Olympic Forest Park on Sunday. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images)

This picture taken on February 24, 2013 shows paticipants taking part in the annual 3.5 km Undie Run held in the Olympic Forest Park in Beijing. Some 300 participants wanted to prove that Chinese can brave the cold just as well as any nationality and promote nationwide fitness. There were no winners, no trophies and no starting gun or finishing line. AFP PHOTOAFP/AFP/Getty Images

This picture taken on February 24, 2013 shows a man running with a gas mask during the annual 3.5 km Undie Run held in the Olympic Forest Park in Beijing. Some 300 participants wanted to prove that Chinese can brave the cold just as well as any nationality and promote nationwide fitness. There were no winners, no trophies and no starting gun or finishing line. AFP PHOTOAFP/AFP/Getty Images

This picture taken on February 24, 2013 shows paticipants taking part in the annual 3.5 km Undie Run held in the Olympic Forest Park in Beijing. Some 300 participants wanted to prove that Chinese can brave the cold just as well as any nationality and promote nationwide fitness. There were no winners, no trophies and no starting gun or finishing line. AFP PHOTOAFP/AFP/Getty Images

This picture taken on February 24, 2013 shows paticipants taking part in the annual 3.5 km Undie Run held in the Olympic Forest Park in Beijing. Some 300 participants wanted to prove that Chinese can brave the cold just as well as any nationality and promote nationwide fitness. There were no winners, no trophies and no starting gun or finishing line. AFP PHOTOAFP/AFP/Getty Images

People take part in the Naked Running competition at Olympic Park on February 24, 2013 in Beijing, China. 300 participants took part in the annual 3.5 km Undie Run, which was held in Beijing's Olympic Forest Park on Sunday. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images)

This picture taken on February 24, 2013 shows paticipants exercising during the annual 3.5 km Undie Run held in the Olympic Forest Park in Beijing. Some 300 participants wanted to prove that Chinese can brave the cold just as well as any nationality and promote nationwide fitness. There were no winners, no trophies and no starting gun or finishing line. AFP PHOTOAFP/AFP/Getty Images

This picture taken on February 24, 2013 shows paticipants taking part in the annual 3.5 km Undie Run held in the Olympic Forest Park in Beijing. Some 300 participants wanted to prove that Chinese can brave the cold just as well as any nationality and promote nationwide fitness. There were no winners, no trophies and no starting gun or finishing line. AFP PHOTOAFP/AFP/Getty Images

This picture taken on February 24, 2013 shows people gathering to watch paticipants taking part in the annual 3.5 km Undie Run held in the Olympic Forest Park in Beijing. Some 300 participants wanted to prove that Chinese can brave the cold just as well as any nationality and promote nationwide fitness. There were no winners, no trophies and no starting gun or finishing line. AFP PHOTOAFP/AFP/Getty Images