An officer wipes sweat off the face of a Chinese People's Liberation Army (PLA) honor guard soldier as they rehearse for a welcoming ceremony for New Zealand's Governor-General Sir Jerry Mateparae at the Great Hall of the People in Beijing, Tuesday, July 21, 2015. (Photo by Mark Schiefelbein/AP Photo)

In this Sunday, April 6, 2014 photo, Valery Palma prepares to blow out the candle on a birthday cake for her one-year-old dachshund Camila, at Camila's birthday party in Mexico City. Palma, who has two dogs, spent $300 on the birthday party for 11 canines and 16 people, complete with cake, presents and snacks, at a dog hotel featuring a gym and massage and aromatherapy services. (Photo by Rebecca Blackwell/AP 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.

Emma Raducanu of Great Britain receives treatment in her women's singles first round match against Bianca Andreescu of Canada during day three of Internazionali BNL D'Italia at Foro Italico on May 10, 2022 in Rome, Italy. (Photo by Alex Pantling/Getty Images)

Female members of police commando march during a ceremony on International Women's Day, at the police headquarters in Islamabad, Pakistan March 8, 2018. (Photo by Faisal Mahmood/Reuters)

A girl smiles during the celebration of Holi at the Art Department of the University of Dhaka in Dhaka, Bangladesh on March 8, 2023. (Photo by Mohammad Ponir Hossain/Reuters)

A fisherwoman repairs the fishing nets at a fishing port during the annual summer fishing ban, which covers the Bohai Sea, the Yellow Sea, the East China Sea, and the waters north of 12 degrees north latitude in the South China Sea, on June 8, 2022 in Wenling, Taizhou City, Zhejiang Province of China. (Photo by Liu Zhenqing/VCG via Getty Images)

Australian surfer Sally Fitzgibbons rides a wave during the 2023 ISA World Surfing Games at the El Tunco beach in El Salvador on June 6, 2023. (Photo by Marvin Recinos/AFP Photo)