Jamaica's Tissanna Hickling competes in the women's long jump qualification during the World Athletics Championships at the National Athletics Centre in Budapest on August 19, 2023. (Photo by Kirill Kudryavtsev/AFP Photo)

Chase Jackson, of the United States, competes during the women's shot put qualification at the 2024 Summer Olympics, Thursday, August 8, 2024, in Saint-Denis, France. (Photo by Ashley Landis/AP Photo)

Military officers look at an AR-10 sniper rifle at LAAD, the biggest military industry expo in Latin America in Sao Paulo, Brazil April 10, 2018. (Photo by Nacho Doce/Reuters)

Canoeists are framed by the tail of a breaching whale in Antarctica in April 2023. The photographer, from California, writes: “It was probably a once-in-a-lifetime moment”. (Photo by Jiahong Zeng/Solent News)

Judges watch athletes during the women's individual compact NH 5km competition at the Nordic Combined World Cup in Ramsau, Austria, Saturday, December 16, 2023. (Photo by Matthias Schrader/AP Photo)

Camera trapper Xavier Hubert-Brierre put this large mirror on the side of a road through the jungle in Gabon and left a camera there to record how the animals would respond to their own reflections. A silverback gorilla thought it was seeing another silverback and responded by trying to scare off the potential challenger… (Photo by Xavier Hubert-Brierre/Johns Hopkins University Press)

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.

Elena Reid of USA looks on with bloody face due to a cut during the Women's WIBF Flyweight Championship fight between Regina Halmich and Elena Reid at the Boerderlandhalle on December 3, 2005 in Magdeburg, Germany. (Photo by Christian Fischer/Getty Images)