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.

Dynam employees say a greeting message as they receive customer-care training ahead of the grand opening of the company's pachinko parlour in Fukaya, north of Tokyo July 29, 2014. Japan's once-booming pachinko industry, grappling with a greying customer base and the threat of new competition from casinos, is adopting a softer touch and smoke-free zones to lure a new generation of players, particularly women. Pachinko, a modified version of pinball, is a fading national obsession, with about 12,000 parlours nation-wide and one in thirteen people playing the game. But that figure is declining as the population shrinks and younger people prefer games on their mobile phones. (Photo by Issei Kato/Reuters)

Toyoda Gosei Co Ltd's personal mobility concept airbag car "Flesby" is displayed at the 44th Tokyo Motor Show in Tokyo, Japan, October 28, 2015. (Photo by Yuya Shino/Reuters)

A Xikrin woman holds her husband's shotgun while he cleans freshly hunted peccary in the river. According to tradition, Xikrin women are not allowed to leave the village while their husbands are out hunting a wife must patiently wait for his return. (Photo and caption by Taylor Weidman)

White lioness Azira lies in the cage with her three white cubs, on February 4, 2014. Zoo owner Andrzej Pabich says white lions often have defects that prevent giving birth, or the mother rejects her cubs, but Azira has been patiently feeding and caring for her little ones. (Photo by Czarek Sokolowski/Associated Press)

Indian paramilitary forces march during the annual Republic Day parade on Rajpath in New Delh, January 26, 2013. Republic Day commemorates the 1950 adoption of India's constitution. (Photo by Kevin Frayer/Associated Press)

In this April 28, 2014 file photo, a woman throws a rock and a bag at police blocking her from getting home in the Huepetuhe district of the Madre de Dios region of Peru. Security forces began destroying illegal gold mining machinery in Peru's southeastern jungle region of Madre de Dios, as authorities began enforcing a ban on illegal mining. (Photo by Rodrigo Abd/AP Photo)

People look at the Turrialba volcano as it spewes ashes on May 20, 2016, in Cartago, Costa Rica. The Turrialba volcano started erupting columns of smoke and ash that the wind extended towards the Costa Rican capital, in what according to experts is the strongest eruption in the past six years. (Photo by Ezequiel Becerra/AFP Photo)