Migrants with a stick, stones and knife fight with each other after a brawl erupted over a place in an overcrowded train heading to the Serbian border at the train station in Gevgelija, The Former Yugoslav Republic of Macedonia, 14 August 2015. (Photo by Georgi Licovski/EPA/EFE)

An actor dressed as Tyrion Lannister, poses for photographers with fake severed head before the screening of final episode of “Game of Thrones” on 20-meter-high screen at RZD Arena in Moscow, Russia on May 20, 2019. (Photo by Maxim Shemetov/Reuters)

British South American Airways hostess Mary Guthrie with a pair of pineapples, on the return of the Lancastrian airliner 'Star Dust' to Heathrow Airport after a test-flight to Buenos Aires, 15th January 1946

A little girl hangs three Siamese kittens on a washing line in a garden in Croydon, London. (Photo by Fox Photos/Getty Images). 14th July 1931

Miss Puerto Rico Stephanie Del Valle (C) reacts after winning in the Grand Final of the Miss World 2016 pageant at the MGM National Harbor December 18, 2016 in Oxon Hill, Maryland. (Photo by Zach Gibson/AFP Photo)

Finding just the right spot above the clouds at Camp 1 on Ama Dablam, Danuru Sherpa uses his iPhone to catch up with friends and family. Even at 18,500 feet (5,654 meters), climbers here can check their email and other dispatches from the world below. (Photo by Aaron Huey/National Geographic)

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.

Sydney resident Virginia Maddock watches the supermoon rise off the Sydney beachside suburb of Wanda, August 10, 2014. Sunday’s moon was at its closest approach to Earth, appearing bigger and brighter than any other moon this year. The moon was 221,765 miles away and looked 16 percent larger and 30 percent brighter than usual. (Photo by Jason Reed/Reuters)