Allie Labutis wears a painted “Merica” on her thigh during the fifth annual Made in America Music Festival in Philadelphia, Pennsylvania September 3, 2016. (Photo by Mark Makela/Reuters)

Fresh produce and baskets of fish surround a woman at the Siti Khadijah market in Kota Bharu, Malaysia. (Photo by Duratul Ain D.)

The “Assignments” exhibition is an annual chance to see the top images by UK photojournalists, as chosen by the British Press Photographers’ Association. Here: Wales’s Cory McKenna dominates Micol DiSegni during their fight at Cage Warriors 97 in Cardiff, 29 September 2018. (Photo by Chris Fairweather/Huw Evans Agency)

(L-R) US singer Halsey, models Gigi Hadid and Bella Hadid and Bebe Rexha (bottom L) clap during 2019 MTV Video Music Awards at the Prudential Center in Newark, New Jersey on August 26, 2019. (Photo by Lucas Jackson/Reuters)

Brick-carving featuring Tang Dynasty (AD 618-907) maids performing musical instruments is seen at the Chinese Music History Museum in Xian University of Architecture and Technology on September 27, 2008 in Xian of Shaanxi Province, China. (Photo by China Photos/Getty Images)

South Korean girl group KARA arrive during the 21st High1 Seoul Music Awards at Olympic gymnasium on January 19, 2012 in Seoul, South Korea. (Photo by Chung Sung-Jun/Getty Images)

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.