A woman walks past a giant Pac-Man in Tokyo's Shinjuku area, Wednesday, August 12, 2015. The three-meter (about nine feet and 10 inches)-tall Pac-Man and other video game characters, made of Lego bricks, were on display to promote the upcoming movie “Pixels”. (Photo by Ken Aragaki/AP Photo)

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.

An Indian labourer sifts coloured powder, known as “gulal”, to be used during the forthcoming spring festival of Holi, inside a factory at Fulbari village on the outskirts of Siliguri on March 6, 2017. Holi, the popular Hindu spring festival of colours is observed in India at the end of the winter season on the last full moon of the lunar month, and will be celebrated on March 13 this year. (Photo by Diptendu Dutta/AFP Photo)

A group of Ring Tailed Lemurs eat from a Thanksgiving spread at the San Francisco Zoo on November 23, 2011 in San Francisco, California. Fifteen lemurs at the San Francisco Zoo were treated to a Thanksgiving feast of green beans, a fruit salad made up of apples, bananas, grapes sweet potatoes and a turkey made out of monkey chow. (Photo by Justin Sullivan/Getty Images)

A Sorb egg painter decorates an Easter egg while using bent spoons full of melted wax as coloring at the annual Easter egg market on March 16, 2013 in Schleife, Germany. Easter is a particularly important time of year for Sorbs, a Slavic minority in eastern Germany, and the period includes the tradition of painting Easter eggs that include visual elements intended to ward off evil. Many Sorbs still speak Sorbian, a language closely related to Polish and Czech. (Photo by Adam Berry)

A combination photo shows some of the colourful doors seen in Rabat's Medina and Kasbah of the Udayas, September 2014. UNESCO made Rabat a World Heritage Site two years ago and media and tour operators call it a “must-see destination”. But it seems the tourist hordes have yet to find out. While visitors are getting squeezed through the better-known sites of Marrakesh and Fez, the old part of Rabat - with its beautiful Medina and Kasbah of the Udayas - remains an almost unspoiled oasis of calm. Smaller and more compact, its labyrinths of streets, passages and dead ends are a treasure trove of shapes and colours, of moments begging to be caught by the photographer's lens. (Photo by Damir Sagolj/Reuters)

A man roasts dog at Langowan traditional market on August 9, 2014 in Langowan, North Sulawesi. The Langowan traditional market is famous for selling a variety of extreme food such as dogs, bats, rats, wild boar, and snakes. (Photo by Putu Sayoga/Getty Images)

A man dressed as a devil poses next to a grafitti of late rebel hero Ernesto "Che" Guevara in the indigenous community of Monimbo in Masaya, Nicaragua, October 16, 2015. People prepare to participate in the popular annual festival called "The Aguizotes" held on the last Friday of October, where residents dress up as characters from legends and folklore mythology of Nicaragua. (Photo by Oswaldo Rivas/Reuters)