A guest dressed as a zombie attends the Middle East Film & Comic Con (MEFCC) in Gulf emirate of Dubai, United Arab Emirates, 11 April 2019. The event runs until 13 April 2019. (Photo by Ali Haider/EPA/EFE)

Indonesian soldiers wearing facemasks and personal protective equipment take a part in a sack race during games to celebrate ahead of the country's 75th Independence Day in Surabaya, East Java on August 14, 2020. Indonesia will mark its 75th Independence Day on August 17. (Photo by Juni Kriswanto/AFP Photo)

A gilrl plays games in a shopping mall in Beijing, China, 24 November 2021. Demographers in China have called for more efficient implementation of supportive measures to encourage births to address the country's dwindling population growth as country's birthrate last year was 8.52 births per thousand people, the lowest level since 1978, according China Statistical Yearbook 2021. (Photo by Wu Hong/EPA/EFE)

A torch bearer poses for photographs during the Olympic Torch Relay Celebration event on July 21, 2021 in Tokyo, Japan. As the Olympic torch relay makes its way around Tokyo, public relays have been cancelled in favour of daily ceremonies held behind closed doors, as authorities act to avoid large gatherings while the country endures a fourth wave of coronavirus. (Photo by Yuichi Yamazaki/Getty Images)

A young sloth named Gloria, that was rescued after being stolen from the wild destined for trafficking, peeks out of the box it is being taken to be released at the city's Botanical Garden in Rio de Janeiro, Brazil, Monday, March 13, 2023. Gloria was cared for by the Free Life Institute NGO that rehabilitates injured wildlife found in the surrounding Rio area and returns them, when possible, back to the wild. Those that are too injured to be released are sent to other rehab centers or sanctuaries to live out their lives in protected environments. (Photo by Bruna Prado/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.

A customer buys a box of bullits and a target of Osama Bin Laden October 3, 2001 at Blue Ridge Arsenal in Chantilly, VA. Guns sales have risen across America since the September 11th terrorist attacks. (Photo by Mark Wilson/Getty Images)

Linda Rooks from Yeovil in Somerset, a hostess at Whipsnade Zoo, wears “Tanga” a 7fy long python as a hat and scarf. (Photo by William Vanderson/Getty Images). 1965