NFL player Rob Gronkowski, of the New England Patriots, from second left, accepts the best comeback athlete award with his brothers, NFL free agent Chris Gronkowski and former NFL player Dan Gronkowski at the ESPY Awards at the Microsoft Theater on Wednesday, July 15, 2015, in Los Angeles. (Photo by Chris Pizzello/Invision/AP Photo)

Demonstrators hold masks depicting Colombian citizen Mile Virginia, who was murdered along with photojournalist Ruben Espinosa and three other women, during a protest in Mexico City, August 16, 2015. Espinosa, a prominent Mexican news photographer was among five people found dead in a middle-class neighborhood of the capital on July 31, 2015. Espinosa, who worked for the weekly magazine Proceso and the photo agency Cuartoscuro, had sought shelter in Mexico City earlier this summer saying he had been followed and threatened in the eastern state of Veracruz. (Photo by Tomas Bravo/Reuters)

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.

New lovebirds boxer Robin Deakin – once known as “Britain's Worst Boxer” – and former UK “Big Brother” star Lisa Appleton go to the boxing gym in London, United Kingdom on September 28, 2016. The pair were seen holding hands in the street on arrival, and they then slogged it out in the ring and fooled about in Robin's gym. (Photo by FameFlynet UK)

A dressed up Oakland Raiders fan poses for photos as she arrives at Azteca stadium in Mexico City, Monday, November 21, 2016. The Oakland Raiders face the Houston Texans at a sold out Azteca stadium. (Photo by Dario Lopez-Mills/AP Photo)

As the sun sets on the Malecon in Havana on Friday January 23, 2015, Surenis Angulo de la Paz, 24, center, dances as group of locals play music around her. Behind her is Fidel Lopez, 55. (Photo by Sarah L. Voisin/The Washington Post)

Children guarded by Hungarian police play on the ground after being detained along with other migrants who illegally crossed from Serbia to Hungary near the village of Asotthalom, Hungary, September 16, 2015. (Photo by Dado Ruvic/Reuters)

A Pakistani feeds his goat wearing the words “Eid Mubarak” or “Eid Greeting”, to be slaughtered on the Muslim holiday of Eid al-Adha, or “Feast of Sacrifice”, in Islamabad, Pakistan on Tuesday, October 15, 2013. Muslims all over the world are celebrating Eid al-Adha by sacrificing sheep, goats, cows and camels, to commemorate the Prophet Abraham's readiness to sacrifice his son, Ismail, on God's command. (Photo by Anjum Naveed/AP Photo)