Prints of R$ 50 Brazilian reais bills sit on a table for inspection at at the Casa da Moeda, the national mint, in the Santa Cruz suburb of Rio de Janeiro, Brazil, on Tuesday, March 5, 2013. Brazil is likely to keep its key interest rate at a record low for the third straight meeting, as policy makers are caught between a fragile economic recovery and faster-than-expected inflation. (Photo by Dado Galdieri/Bloomberg)

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.

Just a week before Rio de Janeiro hosts South America's first Olympics, city residents expressed mixed feelings about the cost and security of the Games, while holding out hope they will bring joy to a nation facing economic and political crises. The conflicted thoughts mirror a recent survey by the Datafolha polling group showing that half of Brazilians were opposed to holding the Games, while 63 percent think the costs of hosting the event will outweigh benefits. (Photo by Pilar Olivares/Reuters)

Bella Hadid smiles as she picks up a camera battery which a photographer dropped on the red carpet, before giving it back as she attends the “Ismael's Ghosts (Les Fantomes d'Ismael)” screening and Opening Gala during the 70th annual Cannes Film Festival at Palais des Festivals on May 17, 2017 in Cannes, France. (Photo by Pascal Le Segretain/Getty Images)

Two women jump into a frozen pond as they compete in the Polar Plunge at Frozen Dead Guy Days in Nederland, Colorado March 14, 2015. The winter festival in the small mountain town commemorates the 1994 discovery of the corpse of Bredo Morstol, which is now housed in a shed on dry ice above the town. (Photo by Rick Wilking/Reuters)

Taylor Swift attends the 2018 American Music Awards at Microsoft Theater on October 9, 2018 in Los Angeles, California. (Photo by Jon Kopaloff/FilmMagic)

Six year old Gillian Smith preparing for the All England Stage Dancing Competition where she has previously won five certificates and a silver medal in the under sevens category. (Photo by Terry Fincher/Keystone/Getty Images). 5th July 1957