Zhu Jianqiang, or “strong-willed pig”, famous for surviving more than a month buried in the ruins after the magnitude-8.0 Wenchuan earthquake in 2008, feeds on food sent by admirers wishing it a safe winter in Jianchuan Museum, Chengdu city, southwest China's Sichuan province, 11 January 2021. (Photo by Rex Features/Shutterstock)

Everyone wants to get something for nothing - whether it's a lucky upgrade that means you can turn left when you get on a plane instead or heading off into the economy seats, or even getting a few extra features thrown in for free when you buy a new car.

As some of the sharpest businesses around, no-one understands this quite as well as casinos and that's why they all have a system that they call comps. It's short for "complimentary offers" and these are special treats specially designed to reward you for your loyalty to the casino in question. They're basically bonuses.

A Gnawa traditional group performs in the city of Essaouira on December 14, 2019, to celebrate the decision of adding the Gnawa culture to UNESCO's list of Intangible Cultural Heritage of Humanity. Gnawa culture, a centuries-old Moroccan practice rooted in music, African rituals and Sufi traditions, was added to UNESCO's list of Intangible Cultural Heritage of Humanity earlier in the week. Gnawa refers to a “set of musical productions, fraternal practices and therapeutic rituals where the secular mixes with the sacred”, according to the nomination submitted by Morocco. Often dressed in colourful outfits, Gnawa musicians play the guenbri, a type of lute with three strings, accompanied by steel castanets called krakebs. (Photo by Fadel Senna/AFP Photo)

An ancient oak tree sits in a Shropshire field as the first signs of Spring begin to show across the United Kingdom on February 19, 2014 in Bridgnorth, England. (Photo by Christopher Furlong/Getty Images)

Two young women huddle up in their coats as they brave the cold in Newcastle, England on February 1, 2019. Women in skimpy dresses and men in t-shirts enjoyed a drink and a dance as they celebrated January finally being over. (Photo by Will Walker/North News and Pictures)

A vehicle leaves light trails in a long exposure photograph as it drives beneath the 500-metre Aperture Spherical Radio Telescope in Pingtang county, China. Construction on the device began in 2011 and is nearing completion. (Photo by Liu Xu/AP Photo)

Khadjou Sambe, 25, surfs off the coast of Ngor, Dakar, Senegal, August 18, 2020. Growing up in the coastal capital of Dakar, Sambe never saw a Black woman surfing the Atlantic swells. As Senegal's first female professional surfer, Sambe is now inspiring the next generation to defy cultural norms and take to the waves as a surfing coach for local girls. “When I am in the water I feel something extraordinary, something special in my heart”, Sambe said. (Photo by Zohra Bensemra/Reuters)

A racegoer reacts to picking a winner in the first race on the third day of the Royal Ascot horserace meeting, which is traditionally known as Ladies Day, at Ascot, England Thursday, June 17, 2021. (Photo by Alastair Grant/AP Photo)