Ahmad Sayed Rahman, a five-year-old Afghan boy who lost his right leg when he was hit by a bullet in the crossfire of a battle, dances with his prosthetic leg at the International Committee of the Red Cross (ICRC) hospital for war victims and the disabled, in Kabul on May 7, 2019. (Photo by Wakil Kohsar/AFP Photo)

Visitors look out from a balcony in a quiet mall area with closed retail shops and restaurants only offering takeaway on Tuesday, May 10, 2022, in Beijing. China's capital began another round of three days of mass testing for millions of its residents Tuesday in a bid to prevent an outbreak from growing to Shanghai proportions. (Photo by Ng Han Guan/AP Photo)

Ivan, a tourist from Russia, takes a selfie at Mai Khao Beach as a plane takes off from Phuket International Airport in Phuket, Thailand, January 17, 2022. (Photo by Jorge Silva/Reuters)

A young woman holds a weapon during a basic combat training for civilians, organized by the Special Forces Unit Azov, of Ukraine's National Guard, in Mariupol, Donetsk region, eastern Ukraine, Sunday, February 13, 2022. The United States is evacuating almost all of the staff from its embassy in Kyiv as Western intelligence officials warn that a Russian invasion of Ukraine is increasingly imminent. (Photo by Vadim Ghirda/AP Photo)

A portrait of a young woman who died during a Russian attack is pictured with flowers next to her fresh grave in the cemetery of in Mykolaiv, southern Ukraine, on March 21, 2022. (Photo by Bulent Kilic/AFP Photo)

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 pangolin carries its baby at a Bali zoo, Indonesia, Thursday, June 19, 2014. The pangolin baby was born on May 31. (Photo by Firdia Lisnawati/AP Photo)

British band Florence and the Machine performs at the Bilbao BBK Live festival in Bilbao, Spain, early 13 July 2018. Bilbao BBK Live festival runs from 12 July to 14 July 2018. (Photo by Miguel Tona/EPA/EFE)