The Jet Propulsion Lab team's RoboSimian robot turns on a valve at a simulated disaster-response course during day one of the Defense Advanced Research Projects Agency (DARPA) Robotics Challenge finals in Pomona, California, June 5, 2015. (Photo by David McNew/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.

Artists perform as people watch from the safety of their cars, during the Art Parking drive-in festival in Prague, Czech Republic, Sunday, April 26, 2020. Artists in Czech Republic are finding different ways to perform as regular theaters remain closed in an effort to stem the spread of coronavirus. (Photo by Petr David Josek/AP Photo)

These are some of the Real Doll bodies made by Abyss Creations being assembled in the factory on Tuesday, September 12, 2017 in San Marcos, California. Customers can dictate their partner’s character by choosing between 18 personality traits including shy, sensual, jealous, moody or talkative. (Photo by Eduardo Contreras/San Diego Union-Tribune via ZUMA/Rex Features/Shutterstock)

A performer dressed as a lobster is seen during a lobster-themed electronic music party at a water park on August 01, 2020 in Hangzhou, Zhejiang Province of China. (Photo by Lian Guoqing/VCG via Getty Images)

Japan Agricultural Cooperation Kagawa employees arrange cubic watermelons to be shipped within the country, in Zentsuji city, Kagawa prefecture, western Japan, Wednesday, June 24, 2020. The about 18x18x18-centimeter (7x7x7-inch) square watermelons, grown in transparent square containers, will be sold for about 10,000 yen ($94) each. (Photo ny Maiko Hirai/Kyodo News via AP Photo)

Buddhists monks and children look out from the rooftop at a Buddhist mission hostel and school for underprivileged children as an international passenger flight takes off at the Netaji Subhash Chandra Bose International Airport as the authorities eased restrictions imposed as a preventive measure against the spread of the COVID-19 coronavirus, in Kolkata on July 5, 2020. (Photo by Dibyangshu Sarkar/AFP Photo)

Hirunika Premachandra, a politician and a leader of Samagi Vanitha Balawegaya, a part of the main opposition party Samagi Jana Balawegaya, hugs a female police member during a protest near Sri Lanka's Prime Minister Ranil Wickremesinghe's private residence, amid the country's economic crisis, in Colombo, Sri Lanka on June 22, 2022. (Photo by Dinuka Liyanawatte/Reuters)