A woman carrying a basket of papayas while walking through a vegetable market in Bangkok, Thailand November 11, 2011. (Photo by Kerek Wongsa/Reuters)

A U.S. Army B-24 Liberator Bomber is hailed by a ground crewman as it takes off over a line of shark- nosed fighter planes at an advanced base in China on a mission on October 10, 1943, to bomb Japanese installations. (Photo by AP Photo)

Rapper Cardi B is seen in Paris, France on September 30, 2019 at Paris Fashion Week. (Photo by Splash News and Pictures)

UK Love Island's Maura Higgins attends the Pretty Little Thing X Molly-Mae party at Rosso on September 01, 2019 in Manchester, England. (Photo by Splash News and Pictures)

American actress Heather Rae Young feeds an alpaca a carrot stick from her mouth during her bridal shower hosted by PETA at Kindred Spirits Care Farm on September 2, 2021. On Thursday morning, PETA and rescued animals from Kindred Spirits Care Farm will host a bridal shower for Heather Rae Young in honor of the longtime animal rights activist and Selling Sunset star’s upcoming nuptials to Tarek El Moussa. (Photo by Snorlax/The Mega Agency)

Made Mohon, the operation manager of Sangeh Monkey Forest, feeds macaques with donated peanuts during a feeding time at the popular tourist attraction site in Sangeh, Bali Island, Indonesia, Wednesday, September 1, 2021. (Photo by Firdia Lisnawati/AP Photo)

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 Capybara bathes in the hot spring water at the Saitama Children's zoo in Higashi Matsuyama city, Saitama prefecture on December 21, 2014. Seven capybaras in the zoo, originally from South America, enjoyed the hot spring water on the chilly winter day in Japan. (Photo by Toshifumi Kitamura/AFP Photo)