Fire blows from a fogging machine as a worker sprays fumigation vapour to stem the spread of dengue virus along a street in Peshawar, Pakistan, October 18, 2021. (Photo by Fayaz Aziz/Reuters)

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.

Greyhounds with stuffed and sprung model monkeys strapped to their backs before a hurdle race at Wellinborough. (Photo by E. Bacon). 21st April 1928

India: A sweeper cleans the side of a road near a replica of the Eiffel Tower amid heavy fog in the early morning in the northern Indian city of Chandigarh January 18, 2010. (Photo by Ajay Verma/Reuters)

American actresses and singers Rachel Zegler and Maya Hawke at the Time100 Next Gala held at Second on October 24, 2023 in New York, New York. (Photo by Nina Westervelt/WWD via Getty Images)

In this June 1, 2016 photo, Maria Arias stands near her kitchen as she puts on earrings while getting ready for school in Caracas, Venezuela. So many students have fainted from hunger at Maria's school that administrators told parents to keep their children home until they could find more food. (Photo by Ariana Cubillos/AP Photo)

A woman made-up with the technique of Body Paint seen during the 2nd Spanish tattoo artists Convention of the Only Tattoo Barcelona in Barcelona, Spain on March 17, 2018. (Photo by Ramon Costa/SOPA Images/Rex Features/Shutterstock)