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.

Geraldine Moodie overcame harsh conditions to become western Canada’s first professional female photographer, capturing beautiful images in the country’s most remote regions. An exhibition, “North of Ordinary: The Arctic Photographs of Geraldine and Douglas Moodie”, is at Glenbow, Calgary, 18 February – 10 September. Here: Inuit woman, Kootucktuck, in her beaded attigi. Fullerton Harbour, Nunavut, February 1905. (Photo by Geraldine Moodie/The Guardian)

A truck driver naps under his truck at the fancy bazaar area during the twelve hours Assam bandh or strike in Guwahati, Assam, India, 23 October 2018. At least 46 organisations are observing a 12-hour bandh across the state to protest against the Centre's bid to clear the Citizenship (Amendment) Bill 2016, in the Winter Session of Parliament. (Photo by EPA/EFE/Stringer)

A woman with a snake on her body, taken in Rio de Janeiro, Brazil, April 2017. A holistic therapist uses snakes to massage her clients – claiming it cures depression and even helps victims of abuse. Instead of traditional massaging techniques, Sarah Zaad uses up to six pythons and boa constrictors on brave customers who want to relax or be treated for mental disorders. The flamboyant therapist from Rio de Janeiro, Brazil believes her snakes have a magic touch, which can benefit people by massaging their bodies. (Photo by Kadeh Ferreira/Barcroft Images)

A Thai visitor appears to be frightened by a life-size Velociraptor model also known as Raptor at the Dinosaur Planet theme park in Bangkok, Thailand, 25 March 2016. The 500 million baht (14 million US dollars or 12 million euro) theme park opening in the Thai capital aimed to attract more than 15,000 visitors a day featuring a chance to experience more than 200 dinosaurs from various species that are brought back to life. (Photo by Rungroj Yongrit/EPA)

Olga Gharkova enters a aromatherapy room at the British Banya bathhouse, Saturday, February 15, 2014, in Krasnaya Polyana, Russia, just a few miles away from the ski slopes where athletes are competing for Olympic medals. (Photo by Jae C. Hong/Associated Press)

A potential bidder carefully examines pieces of Tuna in order to ascertain the quality and to estimate its price ahead of the Tuna auction at the Tsukiji fish market on February 28, 2012 in Tokyo, Japan. (Photo by Daniel Berehulak /Getty Images)

A glass skywalk in Wanyuan, Sichuan province, built along the side of a cliff, is the highest such skywalk anywhere in China on January 31, 2017. Some visitors have been proven to be terrified by the experience had to brace against the wall in fear. (Photo by Chinanew.com/AsiaWire)