An anti-extradition bill protester throws a stone at a police station in Tseung Kwan O residential district, in Hong Kong, China, August 4, 2019. (Photo by Kim Kyung-Hoon/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.

A woman takes a photo of a mural by Berlin-based street artist Eme Freethinker featuring the likeness of US actor Will Smith (R) slapping US comedian Chris Rock during the Oscars ceremony, in Berlin on March 30, 2022. (Photo by John MacDougall/AFP Photo)

Several beaches along South Florida's Atlantic coast line were closed after thousands of sharks were seen migrating in the waters. The sharks were migrating from Boca Raton to Jupiter since the beginning of March, marine biologists told NBC Miami. Photo: A spinner shark swims just offshore on Midtown Beach in Palm Beach on Tuesday. (Photo by Jeffrey Langlois/Palm Beach Daily News)

A participant wrestles with a pig in the “greased pig contest” at the Festival du Cochon (Pig Festival) in Sainte-Perpetue, Quebec August 8, 2015. (Photo by Christinne Muschi/Reuters)

Fishermen use traditional cone-shaped nets on Inle lake in Myanmar in February 2022. The men steer their boats with an oar that they control with their feet. They throw the net into the water and push it down so it sinks to the bottom, then drag it back to the surface with the fish trapped inside. (Photo by Alahattin Kanlioglu/Solent News)

A woman searches for nails and other metal scraps from remains of burned houses that were gutted during a fire at a poor bayside village in the district of Tondo, Manila, Philippines on Friday, May 20, 2022. Investigators said about 300 families became homeless after the fire that happened Thursday night. (Photo by Aaron Favila/AP Photo)