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.

Animal rights groups and PETA stop in front of a Prada store on Rodeo Drive during an anti-fur demonstration urging Black Friday shoppers to stop buying fur-related products on November 25, 2011 in Beverly Hills, California. (Photo by Kevork Djansezian/Getty Images)

A man rides his bike along a controversial bike lane on Prospect Park West on August 17, 2011 in the Brooklyn borough of New York City. In what is being viewed as a victory for the Bloomberg administration, a judge on Tuesday dismissed an effort by Brooklyn residents to remove a bicycle lane installed by the city on Prospect Park West. Mayor Michael Bloomberg, along with his transportation commissioner, Janette Sadik-Khan, has attempted to make New York more bicycle and pedestrian friendly with numerous bike and pedestrian lanes around New York City. The effort has angered some in the city who see the lanes as adding to traffic, taking up parking spaces and a danger to pedestrians. (Photo by Spencer Platt/Getty Images)

The eruption of Cordon Caulle began on June 4, 2011, located in the Region of Los Rios in Chile. For about 12 months, people and animals became accustomed to living with the daily fall of ash, which also caused problems in the air traffic in South America. The explosions and lightning during first days of the eruption could be seen from hundreds of miles around. This photograph was taken on the second night of eruption from the town of Lago Ranco. (Photo and caption by Francisco Negroni/National Geographic Traveler Photo Contest)

ATTENTION! All pictures are presented in high resolution. To see Hi-Res images – just TWICE click on any picture. In other words, click small picture – opens the BIG picture. Click BIG picture – opens VERY BIG picture.

A young exhibitor arrives with her kitten on a lead at the National Cat Club show at Crystal Palace, London. (Photo by Fox Photos/Getty Images). 2nd December 1931

A young arab boy, armed with a rifle and a knife, in the Aden Protectorate near Yemen. (Photo by Richards/Fox Photos/Getty Images). February 1938

Archie, a Chinese Crested dog, sits with his tongue out before the start of the 20th Annual Ugliest Dog Competition at the Sonoma-Marin Fair June 20, 2008 in Petaluma, California. Owners of ugly dogs travel to Petaluma from all over the country to participate in the annual contest. (Photo by Justin Sullivan/Getty Images)

Waura Indians wrestle during this year's “quarup”, a ritual held over several days to honour in death a person of great importance to them, in Xingu National Park, Mato Grosso State, Brazil August 25, 2013. (Photo by Ueslei Marcelino/Reuters)