Trees in a park are illuminated with a red light as a part of an art project in Timmendorfer Strand, northern Germany Wednesday, October 26, 2016. (Photo by Michael Probst/AP Photo)

British fashion model Twiggy plays around on the bumper cars at the Bertram Mills Circus in London, England on January 10, 1967. (Photo by AP Photo)

A lion rests in the Nairobi National Park, Kenya on January 6, 2021. (Photo by Tiksa Negeri/Reuters)

A gallery worker poses with work by artist Elinor Stanley during a press preview of The RA Schools Show 2023 at the Royal Academy of Arts in London, Britain, 08 June 2023. The RA Schools Show 2023 runs from 08 to 25 June 2023 at the Royal Academy of Arts in London. (Photo by Neil Hall/EPA)

Highland dancers compete at Inveraray Highland Games on July 19, 2022 in Inveraray, Scotland. The games are held in the grounds of Inveraray Castle celebrate Scottish culture and heritage with field and track events, piping, highland dancing competitions and heavy events including the world championships for tossing the caber. (Photo by Jeff J. Mitchell/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.

A demonstrator confronts a police officer outside the 18th District Police station during a rally after the death of Walter Wallace Jr., a Black man who was shot by police in Philadelphia, Pennsylvania, U.S., October 27, 2020. (Photo by Bastiaan Slabbers/Reuters)

A woman walks with her daughter through an empty street on April 27, 2020 in Malaga, Spain. Since April 27 children under 12 are allowed to come and go from their homes more freely. Spain has had more than 209,000 confirmed cases of COVID-19 and over 23,000 reported deaths, although the rate has declined after weeks of lockdown measures. (Photo by Daniel Perez Garcia-Santos/Getty Images)