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.

Libyan forces allied with the U.N.-backed government fire weapons during a battle with IS fighters in Sirte, Libya, July 21, 2016. (Photo by Goran Tomasevic/Reuters)

Mosha, the elephant that was injured by a landmine, has her prosthetic leg attached at the Friends of the Asian Elephant Foundation in Lampang, Thailand, June 29, 2016. Mosha was 7 months old when she stepped on a land mine near Thailand’s border with Myanmar and lost a front leg. That was a decade ago... (Photo by Athit Perawongmetha/Reuters)

Ugly dog contestants Sweepee Rambo and owner Jason Wurtz celebrate in winning the 2016 World's Ugliest Dog Contest at the Sonoma-Marin Fair in Petaluma, California, USA, 24 June 2016. (Photo by Peter Dasilva/EPA)

American actor and politician Ronald Reagan stands behind his wife, actor Jane Wyman, who sits down to dinner, circa 1940s. She is seated between two unidentified men, both in military uniforms adorned with Arms Qualification medals, the man on the right with Sharpshooter and Marksman badges and the man on the left, a Captain, with Expert and Sharpshooter badges. Reagan wears a military uniform with Cavalry branch insignia and Wyman wears a black dress with stranded pearl necklace, and a black hat with a veil. (Photo by Hulton Archive/Getty Images)

Two children jumping through a water hydrant's shower on a New York street. They have come from a neighbouring co-educational playgroup organised by the city's Police Department. (Photo by Orlando/Getty Images). 1950

A player breaks with the bottle during the bottle-kicking game in Hallaton, central England April 6, 2015. The game is played between Hallaton and the neighbouring village of Medbourne each Easter Monday in which participants compete to bring the bottle across a stream that separates the villages. The bottle is an old field barrel holding about a gallon of beer. (Photo by Darren Staples/Reuters)

A man holds a metal bar as a weapon during a training day for former soldiers and volunteers train in a makeshift camp in the outskirts of Port-au-Prince, Haiti, October 28, 2015. Haiti disbanded its abusive armed forces two decades ago but uniformed veterans and young recruits are resurfacing to add another destabilising factor to the volatile Caribbean nation already dealing with a political vacuum. (Photo by Andres Martinez Casares/Reuters)