Four-month-old fox cubs squaring up to each other in Walthamstow, England on August 7, 2015. (Photo by Greg Morgan/Barcroft Media)

Attendees at Wizard World Comic Con walk through hallways in Chicago, Illinois, United States, August 22, 2015. (Photo by Jim Young/Reuters)

People are reflected in mirrors as they walk in a busy shopping district in Tokyo, Japan, December 25, 2015. (Photo by Thomas Peter/Reuters)

Ukrainian Air Force officers attend a graduation ceremony at the National University of Defence of Ukraine in Kiev, April 24, 2015. (Photo by Gleb Garanich/Reuters)

A competitor participates in the Tough Mudder challenge near Henley-on-Thames in southern England May 2, 2015. (Photo by Eddie Keogh/Reuters)

A clothing shop displays its merchandise in the rebel-controlled city of Idlib, Syria November 7, 2015. (Photo by Ammar Abdullah/Reuters)

A young woman drinks beer at Hofbraeuhaus beer tent on the opening day of the 2015 Oktoberfest on September 19, 2015 in Munich, Germany. The 182nd Oktoberfest will be open to the public from September 19 through October 4and will draw millions of visitors from across the globe in the world's largest beer fest. (Photo by Johannes Simon/Getty Images)

Victoria's Secret Angel Martha Hunt celebrates the 2015 What Is s*xy? List in San Diego on September 26, 2015 in San Diego, California. (Photo by Joe Scarnici/Getty Images for Victoria's Secret)