A man presents a self-made robot that local media reported is able to carry a person, in Heihe, Heilongjiang province, China, April 5, 2017. (Photo by Reuters/China Daily)

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 girl carries a rifle as she attends a rally by followers of the Shi'ite Houthi movement commemorating the death of Imam Zaid bin Ali in Sanaa, Yemen October 26, 2016. (Photo by Khaled Abdullah/Reuters)

Actor George Clooney is arrested with his father Nick Clooney (2R) during a demonstration outside the Embassy of Sudan March 16, 2012 in Washington, DC. United to End Genocide, the Enough Campaign and Amnesty International held a rally to call on the United States and world leaders to stop the violence in South Sudan and prevent hundreds of thousands of people from starving. (Photo by Win McNamee/Getty Images)

Comedian Jeffrey Ross (C) arrives at Comedy Central's Roast of Charlie Sheen held at Sony Studios on September 10, 2011 in Los Angeles, California. (Photo by Christopher Polk/Getty Images)

“The titan arum or Amorphophallus titanum (from Ancient Greek amorphos, “without form, misshapen” + phallos, “phallus”, and titan, “giant”) is a flowering plant with the largest unbranched inflorescence in the world. The titan arum's inflorescence is not as large as that of the Talipot palm, Corypha umbraculifera, but the inflorescence of the Talipot palm is branched rather than unbranched”. – Wikipedia

Photo: Kew Gardens employee Lauren Bird Royal examines the flowering of the Titan Arum lily at the Botanical Gardens at Kew on September 30, 2005 in London, England. For the first time in horticultural history, the Titan Arum lily can be seen at all three active stages in its lifecycle – in flower, fruit and leaf.The flowering corm is nearly three metres tall and weighs 91kg and is very rarely seen outside of the rainforests of Sumatra, Indonesia. (Photo by Scott Barbour/Getty Images)

A little girl hangs three Siamese kittens on a washing line in a garden in Croydon, London. (Photo by Fox Photos/Getty Images). 14th July 1931

Model feebee poses as part of art installation “Dazzle room” made by artist Shigeki Matsuyama at Room 32 fashion and design exhibition in Tokyo, Friday, February 19, 2016. Matsuyama's installation features a strong contrast of black and white, which he learned from dazzle camouflage used mainly in World War I, in Tokyo, Friday, Feb. 19, 2016. (Photo by Shuji Kajiyama/AP Photo)