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.

Local residents crowd a swimming pool during a hot weather in Suining, Sichuan province, 27 July 2008. (Photo by Reuters/Stringer)

A group of frogs hitched a lift on a passing crocodile. Clearly comfortable in the croc’s company the amphibians wait patiently for their chauffeur to move. But the bemused crocodile doesn’t appear to be going anywhere in a hurry. The hilarious images were captured by Tanto Yensen, 36, from Jakarta, Indonesia. (Photo by Tanto Yensen/Media Drum World Photo Agency)

Two journalists stand on the back of a horse-shaped statue on display to promote the art performance titled “Yu Ma” presented by Taiwan’s Paper Windmills Theater, during a photo call outside the Sun Yat-sen Memorial Hall in Taipei on March 24, 2021. (Photo by Sam Yeh/AFP Photo)

Pitch invader Kinsey Wolanski is taken away by security during the Champions League final soccer match between Tottenham Hotspur and Liverpool at the Wanda Metropolitano Stadium in Madrid, Saturday, June 1, 2019. (Photo by Toby Melville/Reuters)

People participate in the annual “No Pants Subway Ride” in New York City, U.S., January 12, 2020. (Photo by Brendan McDermid/Reuters)

(L-R) Sophie Turner, Priyanka Chopra Jonas, and Danielle Jonas during the 62nd Annual GRAMMY Awards at STAPLES Center on January 26, 2020 in Los Angeles, California. (Photo by Kevin Mazur/Getty Images for The Recording Academy)

Kendall Jenner wearing a bikini and spraying water out of a hose on a photoshoot in Miami on February 5, 2020. (Photo by Splash News and Pictures)