Palestinians fleeing Khan Yunis on the coastal road leading to Rafah further south ride on a donkey-cart with their belongings on January 25, 2024, amid continuing battles between Israel and the Palestinian militant group Hamas. Israel pressed its blistering assault on the Gazan city of Khan Yunis on January 25, with the Palestinian Islamist movement Hamas saying dozens were killed in heavy bombardment and urban combat. (Photo by AFP Photo)

A model presents a creation for Kenzo by Japanese fashion designer Tomoaki Nagao aka Nigo during Kenzo fashion show at the North Bund Bay in Shanghai on July 28, 2023. (Photo by Jade Gao/AFP Photo)

A machine engraves information on an ingot of 99.99 percent pure gold at the Krastsvetmet non-ferrous metals plant, one of the world's largest producers in the precious metals industry, in the Siberian city of Krasnoyarsk, Russia October 24, 2016. (Photo by Ilya Naymushin/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 robot named “Robovie-II”, developed by Japanese robotics research institution ATR, moves around at a grocery store during a shopping assisting experiment by utilizing the robot in an ubiquitous network technology platform in Kyoto, western Japan January 6, 2010. (Photo by Yuriko Nakao/Reuters)

A heat-stressed koala waits as a resident pours water on its back on December 19, 2015 in Adelaide, Australia. Adelaide is experiencing an extreme heatwave, with temperatures reaching over 40 degrees for five consecutive days. (Photo by Morne de Klerk/Getty Images)

A group of Ring Tailed Lemurs eat from a Thanksgiving spread at the San Francisco Zoo on November 23, 2011 in San Francisco, California. Fifteen lemurs at the San Francisco Zoo were treated to a Thanksgiving feast of green beans, a fruit salad made up of apples, bananas, grapes sweet potatoes and a turkey made out of monkey chow. (Photo by Justin Sullivan/Getty Images)

Children look at Hares and Ducks ahead of the Turkey and dressed poultry auction at Chelford Market, northern England December 22, 2014. (Photo by Phil Noble/Reuters)