English actress, television presenter and model Kelly Brook attends the London premiere of Guy Ritchies movie “Snatch” held at the Odeon Leicester Square in London's West End, August 23, 2000. (Photo by Alan Davidson/Rex Features/Shutterstock)

Tourists ride in inflatable boats as they go rafting down a river at Buyun Mountain Scenic Spot on July 10, 2020 in Dalian, Liaoning Province of China. (Photo by Wang Hua/VCG via Getty Images)

Students protest in red underwear on the Plein in The Hague, The Netherlands, 02 June 2021. The action is part of the #NietMijnSchuld campaign by Dutch union FNV Young & United and the National Student Union LSVb, which are campaigning for a debt-free basic grant. (Photo by Bart Maat/EPA/EFE)

Bride Ana Vallejos, wearing a traditional “Caporales” Andean outfit, is escorted by her parents to her wedding celebration, in La Paz, Bolivia, Saturday, December 12, 2020. As a measure to reactivate the economy, the Bolivian government lifted restrictions to help curve the spread of the new coronavirus. Sporting, religious and cultural events may take place publicly until mid-January. (Photo by Juan Karita/AP Photo)

A robot using artificial intelligence is displayed at a stand during the International Telecommunication Union (ITU) AI for Good Global Summit in Geneva, on May 30, 2024. Humanity is in a race against time to harness the colossal emerging power of artificial intelligence for the good of all, while averting dire risks, a top UN official said. (Photo by Fabrice Coffrini/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.

In this Thursday, February 9, 2017 photo, a Bangladeshi boy pulls a rickshaw loaded with strips of leather at the highly polluted Hazaribagh tannery area in Dhaka, Bangladesh. Hazardous, heavily polluting tanneries with workers as young as 14 supplied leather to companies that make shoes and handbags for Western brands, a nonprofit group that investigates supply chains says. (Photo by A.M. Ahad/AP Photo)

A river otter (lontra longicaudis) of 6-weeks-old looks in the mirror during a bath in the Animal Welfare Unit of the Zoo in Cali, Colombia, on October 22, 2019. The baby otter was found abandoned brought to the Cali Zoo for breeding, for its extensive experience in raising these species. According to the International Union for Conservation of Nature the river otter (lontra longicaudis) are in danger of extinction, because of mining, agriculture, pollution of rivers and housing construction in their habitat. (Photo by Luis Robayo/AFP Photo)