A man sleeps between tombstones in front of his single-room home on a hot night in the Cairo Necropolis, Egypt, October 13, 2015. In the sprawling Cairo Necropolis, known as the City of the Dead, life and death are side by side. Amid a housing crisis in Egypt, and with the population of greater Cairo estimated at about 20 million, people count themselves lucky to have a place to call home in the graveyards that date back hundreds of years. (Photo by Asmaa Waguih/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.

Office sеx. (Photo by Orange-Melody/Getty Images)

Actresses Vonnie Lui (R) and Yukiku Suou (L) attend the “3D s*x And Zen: Extreme Ecstacy” photocall at the Majestic Beach Pier during the 64th Cannes Film Festival on May 14, 2011 in Cannes, France. (Photo by Michael Buckner/Getty Images)

English fashion model Daisy Lowe seen at LFW s/s 2018: Off-White x Mytheresa.com – intimate dinner at St John Bar & Restaurant during London Fashion Week September 2017 on September 17, 2017 in London, England. (Photo by MagicMoments UK)

A model is seen backstage before the Spring/Summer 2019 women's ready-to-wear collection show for Y-Vision X Jessie & Jane during Paris Fashion Week in Paris, France, October 1, 2018. (Photo by Stephane Mahe/Reuters)

Model Bella Hadid poses on the red carpet of Rihanna's new Savage X Fenty collection show for New York Fashion Week at the Barclays Center in the Brooklyn borough of New York, U.S., September 10, 2019. (Photo by Shannon Stapleton/Reuters)

In this Wednesday, August 20, 2014 photo released by Red Bull, Maikel Melero of Spain warms up prior to the fifth stage of the Red Bull X-Fighters World Tour in the South African savanna of Pretoria, South Africa. (Photo by Joerg Mitter/AP Photo/Red Bull)