Hollywood actress Malin Akerman helps King Digital Entertainment set the Guinness World Record for the World's Largest Hammock to celebrate the launch of its new game Paradise Bay on Wednesday, September 2, 2015, in Jersey City, N.J. (Photo by Charles Sykes/Invision for King World Entertainment/AP Images)

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.

Residents watch the ocean waves crash into the water front, after the passage of Hurricane Irma, in Cuba, Sunday, September 10, 2017. (Photo by Ramon Espinosa/AP Photo)

Beloni (34) gives a bath to his son, 6, on a small street in the neighborhood of Cite Vincent, on March 21, 2016 in the commune of Cite Soleil in the Haitian capital Port-au-Prince. World Water Day, marked on March 22, 2016, is an international observance to learn more about water related issues and to take action for sustainable management of freshwater resources. (Photo by Hector Retamal/AFP Photo)

A woman cries as she stands next to house destroyed by the earthquake in the Pacific coastal town of Pedernales, Ecuador, Sunday, April 17, 2016. A magnitude-7.8 quake, the strongest since 1979, hit Ecuador flattening buildings, buckling highways along its Pacific coast and killing hundreds. (Photo by Dolores Ochoa/AP Photo)

Poland's Dawid Kubacki soars through the air during the men's FIS Ski Jumping World Cup competition in Engelberg, central Switzerland, on December 20, 2014. (Photo by Fabrice Coffrini/AFP Photo)

Brett Gardner #11of the New York Yankees dives into second base on the back end of an attempted double during the first inning in a MLB baseball game at Yankee Stadium on September 3, 2014 in the Bronx borough of New York City. Gardner was tagged out on the play. (Photo by Rich Schultz/Getty Images)

People take part in the Classic Ride Rally in downtown Valencia, eastern Spain, 23 November 2014. Some hundred people on classic bikes from the 20's to the 70's participated in the rally. (Photo by Kai Foersterling/EPA)