Sofia Evangelia Malkogeorgou and Evangelia Platanioti of Greece perform in the duet technical routine of the artistic swimming event during the Paris 2024 Olympic Games at the Aquatics Centre in Saint-Denis, north of Paris, on August 9, 2024. (Photo by Gonzalo Fuentes/Reuters)

Highland dancers compete at Inveraray Highland Games on July 19, 2022 in Inveraray, Scotland. The games are held in the grounds of Inveraray Castle celebrate Scottish culture and heritage with field and track events, piping, highland dancing competitions and heavy events including the world championships for tossing the caber. (Photo by Jeff J. Mitchell/Getty Images)

Models dressed as showgirls participates in a fashion show in front of the Welcome to Fabulous Las Vegas sign on the Las Vegas Strip to kick off the pro-mask wearing campaign “Mask Up for Nevada” put on by Experience Strategy Associates amid the spread of the coronavirus on June 25, 2020 in Las Vegas, Nevada. On Wednesday, Nevada Gov. Steve Sisolak signed a directive requiring people to wear face coverings in public places throughout the state beginning on June 26 in response to a four-week upward trend of new daily COVID-19 cases. (Photo by David Becker/Zuma Press)

A huge atlas moth, with a wingspan of more than 9in, photographed on an areca nut plantation in Sirsi, India. (Photo by Uday Hegde/Close Up Photographer of the Year)

Beautiful woman and man playing domination games in bed. (Photo by nd3000/Getty Images)

Archie, a Chinese Crested dog, sits with his tongue out before the start of the 20th Annual Ugliest Dog Competition at the Sonoma-Marin Fair June 20, 2008 in Petaluma, California. Owners of ugly dogs travel to Petaluma from all over the country to participate in the annual contest. (Photo by Justin Sullivan/Getty Images)

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 boatman rests on his boat in the flooded Ganges river under the Shastri bridge at Daraganj Ghat, in Allahabad, India on August 22, 2019. (Photo by Sanjay Kanojia/AFP Photo)