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.

Geology Professor Fetullah Arik takes measurements next to a large sinkhole on June 03, 2021, in Karapinar, Turkey. In Turkey’s Konya province, the heart of the country's agriculture sector, extreme drought conditions over the past two years are taking a heavy toll on farmers and the land. (Photo by Chris McGrath/Getty Images)

A kingfisher dives into the leafy water of the River Alde near Rendham, Suffolk in the second decade of November 2022 and catches two fish. Kingfishers must be able to see the fish they want to catch before making their dive, so for this bird to be successful when leaves covered the surface of the water shows its true skill for survival. (Photo by Ivor Ottley/Animal News Agency)

A herd of wild monkeys ask for food from passing vehicles along a mountain road after a snowfall on October 20, 2020 in Luhuo County, Sichuan Province of China. (Photo by Jin Shujie/VCG via Getty Images)

An alligator named Muja is seen in its enclosure in Belgrade's Zoo, Serbia, August 14, 2018. Muja is officially the oldest American alligator in the world living in captivity. He was brought to Belgrade from Germany in 1937, a year after the opening of the Zoo. Muja survived three bombings of Belgrade, the Second World War and all hardships the Zoo went through. (Photo by Marko Djurica/Reuters)

A market trader in Gaibandha in Bangladesh on September 25, 2019, surrounded by bottle gourd vegetables, which sell for around 3p ($ 0.04) each. (Photo by Solent News)

A vender arranges goods for sale at a market on the outskirts of Buenos Aires, Argentina, Wednesday, January 10, 2024. (Photo by Natacha Pisarenko/AP Photo)

A snow leopard looks on from an inside of a cage, after being captured from the southern plains of Nepal and brought to the central zoo, which wildlife experts say is rare for the animal that is found in the higher altitude, in Kathmandu, Nepal on January 26, 2024. (Photo by Navesh Chitrakar/Reuters)