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 commuter gestures to Boris Johnson as he rides across Vauxhall Bridge in London, England on November 19, 2015. The London mayor was opening a cycle superhighway. (Photo by John Stillwell/PA Wire)

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Pro-democracy protesters dressed in traditional Thai costumes take part in an anti-government rally in Bangkok on October 14, 2020. (Photo by Jack Taylor/AFP Photo)

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A professional training in explosive disposal is held in Nanning, Guangxi, China on 18th February, 2021. (Photo by Top Photo Corporation/Rex Features/Shutterstock)