People cross the street in central Pyongyang, North Korea May 4, 2016. (Photo by Damir Sagolj/Reuters)

Lara Stone at Mark's Club on October 27, 2016 in London, England. (Photo by Mark Milan/GC Images)

Festival goers dance during Glastonbury Festival at Worthy Farm, near Pilton, Somerset, Britain, 23 June 2017. The outdoor festival runs from 21 to 25 June. (Photo by Nigel Roddis/EPA)

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.

Londoners sleep on the platform and on the train tracks at Aldwych Underground station,London, during heavy all night Nazi bombing raids, October 8, 1940. (Photo by AP Photo)

Pakistani Rangers (black) and Indian Border Security Force personnel (brown) perform perform during the daily beating of the retreat ceremony at the India- Pakistan Wagah Border Post, some 35 kms west of Amritsar on August 14, 2017. Pakistan celebrates its independence on August 14, one day before India' s independence day on August 15. (Photo by Narinder Nanu/AFP Photo)

In this image released on November 22, English singer and songwriter Dua Lipa poses for the 2020 American Music Awards, broadcast on November 22, 2020 in London, England. (Photo by Gareth Cattermole/Getty Images for dcp)

A man is publicly flogged by a member of the Sharia police after he was found guilty of raping a child, in Idi Rayeuk, East Aceh on November 26, 2020. (Photo by Cekmad/AFP Photo)