A woman participates in a ritual for the African sea goddess Yemanja at Ramirez Beach in Montevideo, Uruguay, Tuesday, February 2, 2021. (Photo by Matilde Campodonico/AP Photo)

A Civil Protection employee dressed as death participates in the campaign “Beware of Monoxide, the Silent Killer”, which seeks to prevent deaths from poisoning with carbon monoxide through the use of heaters to mitigate low temperatures, on an avenue in Ciudad Juarez, Mexico on February 2, 2022. (Photo by Jose Luis Gonzalez/Reuters)

Lava gushes from the southern side crater of Mt. Etna, Europe's largest active volcano, near Catania, southern Italy Sicily, early Tuesday, May 25, 2021. (Photo by Salvatore Allegra/AP Photo)

A woman walks past posters bearing the letter “Z” in the colours of the ribbon of Saint George, which has become a symbol of support for Russian military action in Ukraine, and reading “We are proud of Russia! We are not ashamed!” at a bus stop on Nevsky Prospekt in central Saint Petersburg on March 15, 2022. (Photo by AFP Photo/Stringer)

A mermaid poses under water during a shoot with photographer Brett Stanley during MerMagic Con at the Freedom Aquatic Center in Manassas, Virginia on August 7, 2021. MerMagic Con is advertised as the largest Mermaid convention in the world. Some parts of the convention are based on modeling and looks like the Miss Mermaid USA Pageant. The Society of Fat Mermaids looks to bring together plus size people and promote the idea that anyone can become a mermaid. Becoming a mermaid is not cheap, most merfolk spend thousands of dollars on their tail and outfit. Most tails are custom made out of silicone and others are foam and fabric. (Photo by Joseph Prezioso/AFP 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.

Zoo keepers feed crocodiles in their enclosure at the Madras Crocodile Bank, closed due to the outbreak of coronavirus disease (COVID-19), in Mahabalipuram, India, August 3, 2020. (Photo by P. Ravikumar/Reuters)

A woman carries her baby as she places fishes for sale at a market in Abobo neighborhood, in the suburbs of Abidjan, Ivory Coast, Sunday, November 1, 2020. (Photo by Leo Correa/AP Photo)