Shura Kitata of Ethiopia runs past cardboard cut-outs of the Duke of Cambridge and the Queen at the London Marathon in London, Britain, 04 October 2020. (Photo by Tom Jenkins/The Guardian)

Ella Bucio of Mexico takes part in a training session before Women's Speed Semi Final at the FIG Parkour World Championships in Tokyo on October 15, 2022. (Photo by Philip Fong/AFP Photo)

Lin Yufei and Gao Zijian of China perform in the gala exhibition on day three of the ISU Grand Prix of Figure Skating Cup of China at Huaxi Sports Center on November 8, 2020 in Chongqing, China. (Photo by Carlos Garcia Rawlins/Reuters)

Members of Team Japan compete in the Artistic Swimming Team Acrobatic Final on day four of the Fukuoka 2023 World Aquatics Championships at Marine Messe Fukuoka Hall A on July 17, 2023 in Fukuoka, Japan. (Photo by Quinn Rooney/Getty Images)

Tara Davis-Woodhall, celebrates after winning the women's long jump during the U.S. track and field championships in Eugene, Ore., Sunday, July 9, 2023. (Photo by Ashley Landis/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.

Mud-covered tourists pretend to be trapped inside a mud prison at the Daecheon Beach Mud Plaza in the city of Boryeong on South Korea's west coast, July 17, as they take part in the Boryeong Mud Festival, which opened that day and runs through July 26. Boryeong mud is rich in natural mineral component and is considered to prevent skin aging. (Photo by EPA/Yonhap)

A receptionist dinosaur robot performs at the new robot hotel, aptly called Henn na Hotel or Weird Hotel, in Sasebo, southwestern Japan, Wednesday, July 15, 2015. From the receptionist that does the check-in and check-out to the porter that’s a stand-on-wheels taking luggage up to the room, the hotel, that is run as part of Huis Ten Bosch amusement park, is “manned” almost totally by robots to save labor costs. (Photo by Shizuo Kambayashi/AP Photo)