A Police officer reacts to protestors outside the Piet Retief Magistrates court where the five accused in the shooting of the Coka brothers on the Pampoenkraal farm appeared, Mhkondo, Mpumalanga, South Africa on April 19, 2021. (Photo by Jacques Nelles)

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.

Actors dressed as zombies and ghouls perform during a drive-in haunted house show by Kowagarasetai (Scare Squad), for people inside a car in order to maintain social distancing amid the spread of coronavirus, at a garage in Tokyo, Japan on July 3, 2020. (Photo by Issei Kato/Reuters)

British soldiers inspect a captured German place in the Horseguards' Parade, London during World War I in November 1914, with the London Eye in the background as a reminder of just how much has changed in the last 100 years. (Photo by Peter Macdiarmid/Getty Images)

Labourers carry a basket packed with vegetables through a wholesale market in Kolkata, India, February 26, 2016. (Photo by Rupak De Chowdhuri/Reuters)

People wade past stranded trucks on a flooded street in Sunamganj on June 21, 2022. Floods are a regular menace to millions of people in low-lying Bangladesh, but experts say climate change is increasing their frequency, ferocity and unpredictability. (Photo by Mamun Hossain/AFP Photo)

Human like robots and robotic faces that mimic human expressions are displayed at the annual World Robot Conference at the Beijing Etrong International Exhibition and Convention Center in Beijing, Wednesday, August 16, 2023. (Photo by Ng Han Guan/AP Photo)

A Christmas Tree goes up in flames in a controlled-setting demonstration by the Glendale Fire Department on December 13, 2023, in Glendale, California. Firefighters showed how quickly a dried-out tree can ignite. According to the National Fire Protection Administration, Christmas trees account for hundreds of fires each year, often ignited by shorts in electrical lights or open flames from candles, lighters or matches. (Photo by Frederic J. Brown/AFP Photo)