Genzebe Dibaba of Ethiopia competes in the women's 1500m semi-final during the 15th IAAF World Championships at the National Stadium in Beijing, China August 23, 2015. (Photo by Lucy Nicholson/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.

Mikhail Kalashnikov, the father of the world's most popular assault rifle, is handed an AK-74 November 23, 2002 in Izhevsk,1000 East km. from Moscow. November 23 marked the 55th anniversary of the release of the first Kalashnikov gun. According to the Moscow-based Center for Analysis of Strategic and Technologies some 70 million to 100 million Kalashnikovs have been built worldwide since 1947, compared about 7 million to Kalashnikov's Western rival the M-16 assault rifles. (Photo by Oleg Nikishin/Getty Images)

Yoga students take a class with Nigerian Dwarf goats held by the 'Hello Critter Goat Yoga' team at the Golden Road Pub in Los Angeles, California on May 7, 2018. The goat yoga fitness craze is sweeping the United States with classes now held in pubs, farms and halls across the country. (Photo by Mark Ralston/AFP Photo)

In this photo taken on Saturday, May 2, 2020, funeral workers, wearing protective suits, lower the coffin of Semen Muchka, 71, who died of coronavirus disease, into the grave at a cemetery in Krynytsya, Ukraine. (Photo by Evgeniy Maloletka/AP Photo)

Environmental activist Rob Greenfield walks around Beverly Hills, California on May 16, 2022 wearing a suit filled with every piece of trash he has generated living and consuming like a typical American for one month to raise awareness about how much garbage just one person generates. (Photo by Robyn Beck/AFP Photo)

A woman takes part in a carnival parade as part of New Year's Eve festivities in San Jose, Costa Rica, 27 December 2023. (Photo by Jeffrey Arguedas/EPA/EFE)

New York Yankees' Domingo Germán, center, is doused by teammates after he pitched a perfect game against the Oakland Athletics in a baseball game in Oakland, Calif., Wednesday, June 28, 2023. The Yankees won 11-0. (Photo by Godofredo A. Vásquez/AP Photo)