A soldier walks on the bank of the river in central Pyongyang, North Korea on April 16, 2017. (Photo by Damir Sagolj/Reuters)

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 woman walks in the stairs of the Hotel Martinez in Cannes as the French Riviera prepares for the 2021 edition of the Cannes Film Festival which will take place next July, in France, June 3, 2021. (Photo by Eric Gaillard/Reuters)

Migrants seeking asylum in the U.S., who returned to the Mexican side of the border to avoid deportation, play soccer in a makeshift migrant camp in Braulio Fernandez Ecological Park in Ciudad Acuna, Mexico, September 22, 2021. (Photo by Go Nakamura/Reuters)

A runner dressed as Spiderman poses before the annual “Sao Silvestre Run”, an international race through the streets of Sao Paulo, Brazil on December 31, 2021. (Photo by Carla Carniel/Reuters)

A woman plays on a swing on the beach in Santa Monica, Calif., Wednesday, June 22, 2022. (Photo by Jae C. Hong/AP Photo)

The Balance Bike Quad Eliminator being run (and organised) by GT Bicycles at the Malverns Classic, Start Line, Eastnor Deer Park, Eastnor, in Herefordshire on Friday 26th August 2022. Youngsters enjoy the thrills & spills of balance bike riding as they partake in the annual event held in rural Herefordshire. The thrills and spills as rider No. 013, Kelia Ranes tries hard to avoid a fallen competitor. (Photo by Richard Stanton/The Times)

Fans watch during a match between Daria Kasatkina, of Russia, and Coco Gauff during round-robin play on day four of the WTA Finals tennis tournament in Fort Worth, Texas, Thursday, November 3, 2022. (Photo by Ron Jenkins/AP Photo)