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.

Anja Rubik poses as she arrives for the screening of the film “Dolor Y Gloria (Pain and Glory)” at the 72nd edition of the Cannes Film Festival in Cannes, southern France, on May 17, 2019. (Photo by Stephane Mahe/Reuters)

Model Bella Hadid poses for photographers at the photo call for the film “Pain and Glory” at the 72nd international film festival, Cannes, southern France, Friday, May 17, 2019. (Photo by Arthur Mola/Invision/AP Photo)

Victoria's Secret Angels Candice Swanepoel and Erin Heatherton attend Victoria's Secret Very s*xy Tour stop in New York at the Victoria's Secret at Herald Square on March 13, 2012 in New York City. (Photo by Jamie McCarthy/Getty Images for Victoria's Secret)

(L-R) Mollie King and Frankie Sandford of The Saturdays performs for a dress rehearsal before the first night of their “All Fired Up!” tour at The Bournemouth International Centre on December 1, 2011 in Bournemouth, United Kingdom. (Photo by Dave J. Hogan/Getty Images)

Characters from Star Wars pose for a photocall to promote the release of Star Wars: Episode 1 – The Phantom Menace 3D at The London Eye on February 8, 2012 in London, England. (Photo by Dave J. Hogan/Getty Images)

Mulan Jamilah, a 6-year-old Bengal tiger, kisses caretaker Abdullah Sholeh, 33, in the garden beside their home on January 20, 2014 in Malang, Indonesia.