A mermaids swims 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)

Rosita, a character from the children's television series Sesame Street, gestures in front of Abraham Lincoln's portrait, during an event with children hosted by U.S. first lady Jill Biden of as part of the Christmas decoration and holiday reception kickoff at the White House, in Washington, U.S., November 29, 2021. (Photo by Jonathan Ernst /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.

Battersea Power Station. The chimney rims are thinner on top than you might expect. (Photo by Bradley L. Garrett)

A Ukrainian serviceman of the 65th mechanized brigade smoke on position of a Soviet-made 2s1 Gvozdyka 120mm howitzer in the Zaporizhia region, Ukraine, 15 November 2023, amid the Russian invasion. Russian troops entered Ukrainian territory in February 2022, starting a conflict that has provoked destruction and a humanitarian crisis. (Photo by Kateryna Klochko/EPA)

Salt-resistant plants grow in sand made up of small fish bones on the shore of the Salton Sea before sunrise in an area where a controversial development would create a new town for nearly 40,000 people on the northwest shore of the biggest lake in California, the Salton Sea, on March 21, 2012 south of Mecca, California. (Photo by David McNew/Getty Images)

Hanging bird cages are displayed on poles during a bird-singing contest in the Rueso district in Thailand's southern province of Narathiwat on March 23, 2014. Hundreds of bird owners from Thailand, Malaysia and Singapore took part in the traditional contest held every year. (Photo by Madaree Tohlala/AFP Photo)

Hino Team Sugawara's Teruhito Sugawara with Hirokazu Somemiya and Yuji Mochizuki in action during stage 10 of the Dakar Rally in Saudi Arabia on January 15, 2025. (Photo by Hamad I Mohammed/Reuters)