A participant tries to stay warm during the Macy's Thanksgiving Day Parade in Manhattan,New York, U.S., November 22, 2018. (Photo by Brendan McDermid/Reuters)

A girl walks to a synagogue of the Tzanz Hasidic dynasty community to read the Book of Esther, which tells the story of the Jewish festival of Purim, in Netanya, Israel, Wednesday, March 23, 2016. The Jewish holiday of Purim commemorates the Jews' salvation from genocide in ancient Persia, as recounted in the Book of Esther. (Photo by Ariel Schalit/AP Photo)

A participant dances as approximately 70,000 people from all over the world gathered for the annual Burning Man arts and music festival in the Black Rock Desert of Nevada, U.S. on August 29, 2017. (Photo by Jim Urquhart/Reuters)

In this September 10, 1977, file photo, from left, Hua Guofeng, Chinese Communist Party (CCP) chairman and Mao Zedong's immediate successor; Ye Jianying, CCP vice chairman and future ceremonial head of state; Deng Xiaoping, no formal titles at the time but soon to emerge as paramount leader during the reform era; Li Xiannian, CCP vice chairman and future president; Wang Dongxing, head of the leadership bodyguard unit who helped topple the Gang of Four, view the body of later Chinese leader Mao Zedong in Beijing. (Photo via AP Photo)

Rush-hour in Russia means one thing for this daredevil: train surfing! The 19-year-old daredevil who goes by the name Kobzarro started train surfing aged 15 as a way of escaping an oppressive family life. Here Kobzarro can be seen balanced on top of a train as it speeds through the wintery Russian environment. Kobzarro is so dedicated to train surfing that she rarely gets inside a train. Even in winter she prefers to travel in this less conventional way. It has resulted in a few run ins with the law, but Kobzarro says it has never resulted in anything more serious than a fine, with many police officers even being interested in the train surfing community. (Photo by Caters News Agency)

Participants lay down on a street covered by coloured powder during the annual Bangkok Color Run in Bangkok, Thailand April 1, 2017. (Photo by Athit Perawongmetha/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.