Princess Charlene poses after the arrival of the Riviera Water Bike Challenge in support of the Princess Charlene of Monaco Foundation, in Nice, France, June 4, 2017. (Photo by Eric Gaillard/Reuters)

A reveller performs while attending the block party “Galo da Madrugada” during carnival festivities in Sao Paulo, Brazil on February 25, 2020. (Photo by Rahel Patrasso/Reuters)

An eight-year-old St Bernard with the longest canine tongue in the world, measuring 18.58cm (7.31in) in length, as recorded by the Guinness World Records: Amazing Animals, in South Dakota, USA. (Photo by Kevin Scott Ramos/GWR/PA Wire)

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 small flock of birds seems to be giving an escort to an airliner on final approach to Reagan Washington National Airport in Arlington, Virginia on January 12, 2022. The scene took place over Gravelly Point which is an area within the National Park Service's George Washington Memorial Parkway. (Photo by Michael S. Williamson/The Washington Post)

Vinaya Vijay, right, and Vijay Parthasarathy wade through water at Badwater Basin, Thursday, February 22, 2024, in Death Valley National Park, Calif. The basin, normally a salt flat, has filled from rain over the past few months. (Photo by John Locher/AP Photo)

The Royal Conservatoire of Scotland has appeared in the world top ten for performing arts education in the QS World University Rankings 2024 published today, April 10, 2024. (Photo by The Times)

This photo taken on October 23, 2022 shows a soap bubble reflecting the Namsan Seoul Tower at Namsan Park in Seoul, South Korea. (Photo by Xinhua News Agency/Rex Features/Shutterstock)