A participant, called a musher, races in the 33rd Aviemore Sled Dog Rally in Aviemore, Scotland January 23, 2016. The Siberian Husky Club of Britain is holding its annual sled dog rally over the weekend. (Photo by Russell Cheyne/Reuters)

U.S. Air Force pilots with the Thunderbirds perform the calypso pass maneuver in F-16 Fighting Falcon aircraft during a practice session prior to the Gunfighter Skies air show at Mountain Home Air Force Base, Idaho, September 19 and released September 24, 2014. (Photo by Tech. Sgt. Manuel J. Martinez/Reuters/US Air Force)

A woman rides a custom bike during "Bike Kill 12" in the Brooklyn borough of New York City, October 31, 2015. "Bike Kill" is an annual gathering of builders and riders of home-made bicycles that culminates in a tall bike jousting competition. (Photo by Stephanie Keith/Reuters)

A competitor poses before the Tough Guy Challenge endurance race on January 27, 2013 in Telford, England. Every year thousands of people run the 8 mile assault course which involves freezing temperatures, fire and ice. (Photo by Michael Regan)

Runners use headtorches as they compete in Centurion South Downs Way 100 ultramarathon, at Firle Bostal near Lewes, south of London on June 9, 2024. The Centurion South Downs Way 100, is an ultramarathon, predominantly off road course, covering a distance of 100 miles (160,9 kilometres) and that takes the competitors along the South Downs Way from Winchester in Hampshire to Eastbourne in East Sussex. (Photo by Ben Stansall/AFP Photo)

A chimpanzee bottle-feeds a lamb at Southam Zoo Farm in Warwickshire. The owners of the zoo, Mr and Mrs Clews, bring up many of the animals as their pets; the animals, are, as a result, of a friendly disposition. (Photo by Fox Photos/Getty Images). 23rd August 1968

A man has an egg smashed on his head to raise money for charity during the World Egg Throwing Championships and Vintage Day in Swaton, Britain June 28, 2015. (Photo by Darren Staples/Reuters)

A child dressed as a cat takes part in the Children's Halloween day parade at Washington Square Park in the Manhattan borough of New York October 31, 2015. (Photo by Carlo Allegri/Reuters)