Arizona Cardinals cheerleader Claire Thorton, center, smiles as Air Force Capt. Eric Straub proposes to her during the first half of an NFL football game against the Washington Redskins, Sunday, October 12, 2014, in Glendale, Ariz. Thorton accepted the proposal. (Photo by Rick Scuteri/AP Photo)

“Show Time”. It's a normal behavior of mantis. They're doing defence. When they're afraid of; raising their arms and spreading their wings. They looks like smiling dancer. Photo location: Nicosia, Cyprus. (Photo and caption by Hasan Baglar/National Geographic Photo Contest)

Tour guides wearing traditional Chinese dress practice smiling by biting chopsticks at Qingming Grand-River Park in Kaifeng, central China's Henan Province on March 2, 2017, aiming to provide better service for visitors. (Photo by IPA Asia via ZUMA Wire)

A Maasai woman smiles as Camilla, Duchess of Cornwall is presented with a traditional Maasai necklace as Prince Charles, Prince of Wales looks on during a visit to Majengo Maasai Boma on November 9, 2011 in Arusha, Tanzania. (Photo by Chris Jackson/Getty Images)

Meet Booboo, the 2-year-old guinea pig. Her hobbies included eating chicory and posing for pictures. Described optimistically as ‘spirited’ by owner Megan, she can generally be found knocking about with her guinea pig crew, Titi and Teddy. But don’t worry, these gangsta guineas are lovers not fighters (didn’t the chicory give you a clue?). In fact, they’re pretty cerebral, often to be found quietly reading a book, or staring contemplatively into the distance next to a sprig of lavender, that kind of thing.

Disappointed Cat aka Foo-Chan is a three-year-old Chinchilla Golden has a heavy-set brow, causing him to appear depressed; his gloomy disposition has gone viral on a Japanese forum, where he's been praised as "cute, but troubled" or "worried all the time".

Photographer and animal lover Chris Keeney shows how to use a PetCam with your own pet and offers expert technical know-how and inspiring creative suggestions to get you started. This is Coulee, a border collie/golden retriver mix from Lethbridge, Alberta, Canada. (Photo by Chris Keeney/Princeton Architectural Press)

Students attend a stewardess skill training for the upcoming 2017 entrance examination for art majors in colleges in Luoyang, central China's Henan Province, January 4, 2017. Along with how to stand, how to sit is also covered in these classes. (Photo by Li Bo/Xinhua/Barcroft Images)