In this Sunday, May 29, 2016 photo, fighters take a selfie while firing artillery during fight against Islamic State militants in Fallujah, Iraq. Iraqi forces this week pushed into the city's southern sections after securing surrounding towns and villages more than 50,000 people are believed to be trapped inside the Sunni majority city, about 65 kilometers (40 miles) west of Baghdad. (Photo by Anmar Khalil/AP Photo)

A competitor wearing a kilt and standing on a barrel throws a bowling ball between her legs during the “Brigaball” contest at the annual Bundanoon Highland Gathering, showcasing traditional Scottish events, held in the town of Bundanoon, located southwest of Sydney, April 9, 2016. (Photo by David Gray/Reuters)

Monsoon thunderstorm in Sierra Vista, Arizona. 9 Sept, 2011. (Photo by Steven Maguire)

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.

An Indian villager tries to tame a bull during a traditional bull-taming festival called “Jallikattu”, in the village of Palamedu, near Madurai, Tamil Nadu state, India, Monday, January 15, 2018. Jallikattu involves releasing a bull into a crowd of people who attempt to grab it and ride it. (Photo by R. Parthibhan/AP Photo)

Aerial view of a clear and turbid landscape at the intersection of the Sanjiang Estuary during the flood season on July 4, 2023 in Nanning, Guangxi Zhuang Autonomous Region of China. (Photo by Chen Guanyan/China News Service/VCG via Getty Images)

Primary school students write Chinese character “Ren”, meaning “human being”, during the First Writing Ceremony, a traditional education activity, on September 6, 2023 in Qingdao, Shandong Province of China. (Photo by VCG/VCG via Getty Images)

An Afghan driver stands amid boxes of dry food next to his damaged truck at the site of an accident near the Pakistan-Afghanistan border crossing point in Chaman, Pakistan on August 20, 2021. (Photo by AFP Photo/Stringer Network)