A man carrying a woman wades through a flooded road following heavy rainfall in Zhengzhou, Henan province, July 21, 2021. At least 25 people have died in China's flood-stricken central province of Henan, a dozen of them in a subway line in its capital that was drenched by what weather officials called the heaviest rains for 1,000 years. (Photo by China Daily via Reuters)

A zookeeper wearing orangutan costume tries to escape while zookeepers hold up a net in an attempt to capture it during an Escaped Animal Drill at Tama Zoological Park in Tokyo, Japan on February 22, 2019. The annual escape drill is held to train zookeepers what to do in the event of an animal escape. This year a member of staff wearing an orangutan costume was captured and subdued with large nets, sticks and tranquilizer guns to make sure the orangutan did not get away. (Photo by Rodrigo Reyes Marin/ZUMA Wire/Alamy Live News)

A displaced Yemeni woman from Hodeida fills water containers at a make-shift camp in a village in the northern district of Abs in the country's Hajjah province, on May 9, 2019. The Yemeni conflict has triggered what the United Nations describes as the world's worst humanitarian crisis, with 3.3 million people still displaced and 24.1 million in need of aid. (Photo by Essa Ahmed/AFP Photo)

A female sniper of the Syrian Democratic Forces (SDF) monitors the area during a celebration at the iconic Al- Naim square in Raqa on October 19, 2017, after retaking the city from Islamic State (IS) group fighters. The SDF fighters flushed jihadist holdouts from Raqa' s main hospital and municipal stadium, wrapping up a more than four- month offensive against what used to be the inner sanctum of IS' s self- proclaimed “caliphate”. (Photo by Bulent Kilic/AFP Photo)

Heesco, Windsor. Born and raised in Mongolia and now living and working in Melbourne, Heesco is well known for his skill in rendering photo-realistic portraits. They speak to the viewer in a way that the subtext is enjoyable to decipher. Just what is the Blue Lady’s message? The sunglasses might mask the confronting gaze but her body language fills in the gaps. Heesco’s characters often wear traditional jewellery and clothing that remind us of his Mongolian cultural heritage. (Photo by Lou Chamberlin/The Guardian)

A staff member removes a coffin from a room of the “Corpse Hotel” in Kawasaki, Japan, April 20, 2016. Many so-called corpse hotels have emerged as a flourishing business in the city following a crunch in crematoriums. Families can rent a room in Sousou on a daily charge of 9,000 Japanese yen (£58, €74, $84) to keep the body of the deceased relative for up to four days until they find a crematorium. (Photo by Thomas Peter/Reuters)

A fisherman carries a silver carp during a traditional fish haul at the Horusicky pond near the town of Veseli nad Luznici, Czech Republic, Tuesday, October 24, 2017. Each autumn, Czech fishermen get to serious business of a century-long tradition of catching carp for Christmas markets. Southern Bohemia, where the Horusicky pond is located, with its elaborate network of ponds is at the center of the local carp universe. (Photo by Petr David Josek/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.