Sandra Brown, 40, rides the Skyslide on the 69th and 70th floors of the U.S. Bank Tower which is attached to the OUE Skyspace LA observation deck in downtown Los Angeles, California, U.S. June 20, 2016. (Photo by Lucy Nicholson/Reuters)

Aspiring models wait for their turn to be judged during auditions for the upcoming Lakme Fashion Week in Mumbai, India, June 30, 2016. (Photo by Shailesh Andrade/Reuters)

Attendees dressed as Poison Ivy and Harley Quinn arrive for opening day of the annual Comic-Con International in San Diego, California, United States July 21, 2016. (Photo by Mike Blake/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.

Bahamas' Shaunae Miller-Uibo celebrates winning the women's 200 meters final at the Diamond League Birmingham Grand Prix in Birmingham, Britain on August 18, 2019. (Photo by Jason Cairnduff/Action Images via Reuters)

Pablo Holcer tests out a VR system made by Neurable that allows the user to control with their thoughts as the EEG headset interprets thoughts into actions in the VR environment at SIGGRAPH 2017 in Los Angeles, California, July 31, 2017. (Photo by Mike Blake/Reuters)

Nana Takano and Kaito Toyoshima, winners of the Shanghai preliminary and Asian Championship, compete in the final of the World Tango Championship final in Buenos Aires, Argentina, 27 August 2024. (Photo by Juan Ignacio Roncoroni/EPA)

A former Gurkha (special forces soldier), Nirmal Purja, takes a selfie at the start of his attempt to scale the world’s 14 highest peaks in seven months to break a 31-year-old record. Nirmal Purja, known as Nims, aims to smash the current record – which stands at seven years, 11 months and 14 days – set by Polish climber Jerzy Kukuczka. On the way, he also plans to defeat at least seven speed world records on mountains over 8,000m high. (Photo by Nirmal Purja/PA Wire Press Association)