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.

Women wearing traditional hats, known as a non la, sell fruits in Hoi An, Vietnam April 4, 2016. The non la hats are made of readily available materials such as palm leaves, tree bark and bamboo and are visible everywhere in the city, a UNESCO World Heritage site. Hoi An's history as a busy trading port is evident throughout its architecture, a mix of eras and styles, with traditional wooden Vietnamese houses, Chinese temples and French colonial buildings. (Photo by Jorge Silva/Reuters)

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)

AP photographer Anja Niedringhaus laughs as she attends a swimming event at the 2004 Olympic Games in Athens, August 21, 2004. Niedringhaus, a veteran Associated Press photographer who had covered wars around the world was shot dead and another reporter was wounded on April 4, 2014 when an Afghan policeman opened fire on them in eastern Afghanistan, the news agency said. (Photo by Reuters/Staff)

A girl presents the new Oktoberfest beer festival mug in a Oktoberfest tent in Munich, southern Germany, on August 21, 2014. The world famous beer festival Oktoberfest will takes place from September 20 to October 5, 2014. (Photo by Christof Stache/AFP Photo)

A 6-month old female giant panda cub, an offspring of Xing Xing, formerly known as Fu Wa and Liang Liang, formerly known as Feng Yi, plays at the Giant Panda Conservation Center at the National Zoo in Kuala Lumpur, Malaysia, Thursday, February 18, 2016. (Photo by Joshua Paul/AP Photo)

In this March 7, 1991 file photo, a U.S. Marine patrol walks across the charred oil landscape near a burning well during perimeter security patrol near Kuwait City. Twenty five years after the first U.S. Marines swept across the border into Kuwait in the 1991 Gulf War, American forces find themselves battling the extremist Islamic State group, born out of al-Qaida, in the splintered territories of Iraq and Syria. The Arab allies that joined the 1991 coalition are fighting their own conflicts both at home and abroad, as Iran vies for greater regional power following a nuclear deal with world powers. (Photo by John Gaps III/AP Photo)

A woman reacts as she poses with a man dressed up as the Star Wars character Chewbacca outside the Dolby Theatre, the site of the 88th Academy Awards in Hollywood, California February 26, 2016. (Photo by Adrees Latif/Reuters)