Members of the Unidos da Tijuca samba school parade at the “Opening of Carnival 2022” event, at the Cidade do Samba, in Rio de Janeiro, Brazil, 27 February 2022. The event is a preview of the parades of the Samba Schools of the Special Group, postponed to April due to the COVID-19 pandemic in Brazil. (Photo by Andre CoelhoEPA/EFE)

A billboard depicting a soldier, with a slogan reading “Contract service. A real man's job”, in St. Petersburg, Russia, 02 June 2023. On 24 February 2022, Russian troops entered Ukrainian territory in what the Russian president declared a “Special Military Operation”, starting an armed conflict. (Photo by Anatoly Maltsev/EPA)

Female Ukrainian cadets, wearing new military uniforms designed specially for women, take part in a training during the "Uniform matters" event organised to present the outfit and test it under military training conditions, on the outskirts of Kyiv on July 12, 2023. (Photo by Sergei Supinsky/AFP Photo)

A Kashmiri girl holds her brother in the doorway of their home while watching protesters shout pro-freedom and anti-Indian slogans during mourning and protests held in downtown Srinagar on August 22, 2016, following the killing of teenager Irfan Ahmed by security forces. Teenager Irfan Ahmed was killed after he was hit in the chest by a teargas canister fired by Indian security forces to quell pro-freedom protests in the Kashmiri capital on August 21. More than 60 civilians have been killed in clashes between protesters and security forces, and thousands more injured in the worst violence to hit the Himalayan region since 201. Indian-administered Kashmir has been in the grip of almost daily anti-India protests and rolling curfews sparked by the killing on July 8 of a popular rebel leader, Burhan Wani, in a gunfight with government forces. (Photo by Tauseef Mustafa/AFP Photo)

Trainers from Tianjiao Special Guard/Security Consultant Ltd. Co. engage trainees dressed in swimming suits as they crawl on the beach during a training session in Sanya, Hainan province January 8, 2012. (Photo by CHINA DAILY/Reuters)

Dutch artists Lernert and Sander cut raw food into 98 perfect 2.5 x 2.5 x 2.5 cm cubes, creating a tantalizing geometric display. This viral photo was commissioned by Dutch newspaper de Volkskrant for their their food-themed documentary photography special.

Tibetan men get ready to perform a traditional dance during a special prayer ceremony on the third day of the Tibetan New Year celebrations in Kathmandu, Nepal, Wednesday, March 1, 2017. Tibetans follow this ritual called “sangtsol” to ask for good luck in the new year. (Photo by Niranjan Shrestha/AP 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.