Aimee, 19, who has Down syndrome, has make-up applied by her mother before a presentation in Monterrey, Mexico, in this picture taken April 9, 2016. The association “Abrazame con Discapacidad” (“Embrace me with Disabilities”) teaches folk dance to low-income people with Down syndrome and manages presentations at public events where they receive a payment, as part of a therapy that helps improve their motor system, learning and self-esteem, the association said. (Photo by Daniel Becerril/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.

An Indian lift operator stands inside a dedicated lift for people suspected to be infected with the new corona virus at the Government Gandhi Hospital in Hyderabad, India, Monday, March 2, 2020. Coronavirus has spread to more than 60 countries, and more than 3,000 people have died from the COVID-19 illness it causes. (Photo by Mahesh Kumar A./AP Photo)

A security officer looks at a scanning screen for checking passengers' temperature at the Istanbul Airport in Istanbul, Turkey, on June 9, 2020. Technology and innovation will top the precautions of Turkey's biggest airport Istanbul Airport against the COVID-19 in the post-pandemic era, according to the management of the airport. The management on June 9 presented their final preparations and measures taken against coronavirus while Turkish airline companies are preparing to resume their international operations the next day. (Photo by Yasin Akgul/Xinhua News Agency via Getty Images)

A Palestinian girl watches from the balcony of her house as Israeli soldiers conduct a security operation in the village of Aqraba, east of Nablus in the occupied-West Bank, on May 3, 2021. Suspected Palestinian gunmen carried out a drive-by shooting at a nearby junction the previous, leaving three Israeli civilians wounded, one of them in critical condition, with a manhunt underway. (Photo by Jaafar Ashtiyeh/AFP Photo)

A passenger (C) climbs through the window of an overcrowded bus as limited public transportation operates in the city during the ongoing fuel crisis in Kathmandu, Nepal October 9, 2015. Nepal is considering air-lifting fuel, possibly from Bangladesh, as supply routes from India stay blocked by protesters opposing its new constitution, a short-term solution ahead of a key festival even as the government talks to China for help. (Photo by Navesh Chitrakar/Reuters)

This handout picture taken and released by the Borneo Orangutan Survival Foundation (BOSF) on October 26, 2015 shows baby orangutans, which had previously suffered from respiratory problems, playing at a nursery in the rehabilitation centre operated by the BOSF on the outskirts of Palangkaraya in Central Kalimantan. Endangered orangutans are falling victim to a devastating haze crisis that has left them sick, malnourished and severely traumatised as fires rage through Indonesia's forests, reducing their habitat to a charred wasteland. (Photo by AFP Photo/Borneo Orangutan Survival Foundation/Indrayana)

Michael Read, director of Flight Operations from New Zealand-based Martin Aircraft Company, flies a Martin Jetpack during a demonstration at a water park in Shenzhen, China December 6, 2015. KuangChi Science Ltd, a Hong Kong-listed Chinese company and investor of Martin Aircraft, will sell the flying machine in mainland China for 1.6 million yuan ($249,902), according to the company. (Photo by Bobby Yip/Reuters)