Finia, a visiting student from Hanover, cools off under a water sprinkler in front of the Chancellery on June 10, 2010 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

Linda Rooks from Yeovil in Somerset, a hostess at Whipsnade Zoo, wears “Tanga” a 7fy long python as a hat and scarf. (Photo by William Vanderson/Getty Images). 1965

A German Air Force Officer sits astride a dead boar outside a house where he is stationed near the Western Front, in this 1918 handout picture. This picture is part of a previously unpublished set of World War One (WWI) images from a private collection. The pictures offer an unusual view of varied and contrasting aspects of the conflict, from high tech artillery to mobile pigeon lofts, and from officers partying in their headquarters to the grim reality of life and death in the trenches. The year 2014 marks the centenary of the start of the war. (Photo by Reuters/Archive of Modern Conflict London)

The new Toyota Concept-i concept car, designed to learn about its driver is unveiled during the Toyota press conference at CES in Las Vegas, January 4, 2017. (Photo by Rick Wilking/Reuters)

Just a week before Rio de Janeiro hosts South America's first Olympics, city residents expressed mixed feelings about the cost and security of the Games, while holding out hope they will bring joy to a nation facing economic and political crises. The conflicted thoughts mirror a recent survey by the Datafolha polling group showing that half of Brazilians were opposed to holding the Games, while 63 percent think the costs of hosting the event will outweigh benefits. (Photo by Pilar Olivares/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.

Astronaut Chris Hadfield Explains How to Wash your Hands in Space.

Actor Rarmian Newton who plays the character Hiccup rides Toothless during a scene run through of the “How to Train Your Dragon Arena Spectacular” at Hisense Arena on March 7, 2012 in Melbourne, Australia. (Photo by Robert Cianflone/Getty Images)