This picture taken on January 25, 2015 shows a participant taking part in an ice water challenge in Zhangjiajie, central China's Hunan province. Participants were required to stay in an ice pond, holding an ice block while eating ice-cream with an electric fan blowing at them. (Photo by AFP Photo/Stringer)

A man wears a sweater covered in Irish themed pins as he stands with thousands of spectators to watch the 254th New York City St. Patrick's Day parade up 5th Avenue in the Manhattan Borough of New York, March 17, 2015. (Photo by Mike Segar/Reuters)

Devotees push the chariot of Rato Machhindranath during the chariot festival at Bungamati in Lalitpur April 22, 2015. Rato Machhindranath is known as the god of rain and both Hindus and Buddhists worship Machhindranath for good rain to prevent drought during the rice harvest season. (Photo by Navesh Chitrakar/Reuters)

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.

A Snowboarder participates in a waterslide contest, which consists of gliding over a water pool embedded in snow, during the closing event of the ski resort of Nendaz, southwestern Switzerland, Monday, April 21, 2014. (Photo by Maxime Schmid/AP Photo/Keystone)

Dressed a Royal Canadian Mounted Police officer, Stephane Delage carries a Canadian flag while on stilts as he entertains the crowd during Canada Day festivities in Vancouver, B.C., on Monday, July 1, 2013. (Photo by Darryl Dyck/The Canadian Press)

NFL player Rob Gronkowski, of the New England Patriots, from second left, accepts the best comeback athlete award with his brothers, NFL free agent Chris Gronkowski and former NFL player Dan Gronkowski at the ESPY Awards at the Microsoft Theater on Wednesday, July 15, 2015, in Los Angeles. (Photo by Chris Pizzello/Invision/AP Photo)

Young monks laugh at their own photos taken by a German photojournalist in the main courtyard of the Dzong on October 13, 2011 in Punakha, Bhutan. King Jigme Khesar Namgyel Wangchuck, 31 and Queen of Bhutan Ashi Jetsun Pema Wangchuck, 21 wed in Bhutan's historic 17th century Punakha Dzong the same venue that hosted the King's historical coronation ceremony in 2008. (Photo by Triston Yeo/Getty Images)