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 picture made available on 21 July 2016 shows a visitor having a meal from a toilet bowl at “Jamban Cafe” (lit. Toilet Cafe) in Semarang, Central Java, Indonesia, 16 July 2016. The cafe was created by a sanitation expert for education purposes to stress the importance of using a dedicated toilet and keeping it clean to prevent disease. (Photo by EPA/Purwanto)

Smithfield meat porters march on the Home Office, bearing a petition which calls for an end to all immigration into Britain, 25th August 1972. (Photo by Keystone/Hulton Archive/Getty Images)

Kumari Samita Bajracharya sits in front of devotees offers during a special puja at Kumari Ghar in Patan, Nepal, 09 April 2011. It is believed that worshipping Kumari and receiving tika from her reduces illness and avoid problems. Kumari, or Kumari Devi, is a “living goddess”. The word literally means virgin in Nepali. The Living Goddesses are young pre-pubescent girls that are considered to be incarnations of the Hindu Goddess of Power, Kali. The Kumari retires when she reaches puberty. (Photo by Narendra Shrestha/EPA)

The winners of The London’s Natural History Museum's prestigious Wildlife Photographer of the Year for 2013 have finally been unveiled. Selected from almost 43,000 entries from 96 countries, the winners offer a glimpse of the stunning array of natural beauty on our planet. Photo: Canada: “Lucky pounce”. “Anticipating the pounce – that was the hardest part”, says Connor, who had come to Yellowstone National Park, Wyoming, USA, in search of wildlife as much as the spectacular landscape. He had found this fox, his first ever, on his last day in the park. It was so absorbed in hunting that Connor had plenty of time to get out of the car and settle behind a rock. It quartered the grassland, back and forth, and then started staring intently at a patch of ground, giving Connor just enough warning of the action to come. When it sprung up, Connor got his shot. And when it landed, the fox got his mouse. (Photo by Connor Stefanison/Wildlife Photographer of the Year 2013)

More than 1,200 vintage posters that would send any movie buff into orbit were discovered in an Ohio garage, including the only known copy of an almost 7-foot-tall creation for the 1947 reissue of “Dracula” that could sell for $40,000. The Dallas-based Heritage Auctions in Dallas puts them all on the block March 22 and 23, including some rare specimens from the silent movie era. (Photo by Courtesy Heritage Auctions)

“Misty Morning”. Every morning, people expect sunny weather. Photo location: Bali, Indonesia. (Photo and caption by Henry Adam/National Geographic Photo Contest)

Onlookers gather around a struggling beached whale in the Yoff neighborhood of Dakar, Senegal Wednesday, May 21, 2008. Residents worked Wednesday morning to save some of the more than 80 whales that were stranded on the beach Tuesday night. This whale was successfully towed out to sea by a fishing boat, though at least 20 others lay dead on the beach by midday Wednesday. (Photo by Rebecca Blackwell/AP Photo)