A family poses for a picture in front of the carcasses of sacrificed buffalos a day after the sacrificial ceremony of the “Gadhimai Mela” festival held in Bariyapur November 29, 2014. Sword-wielding Hindu devotees in Nepal began slaughtering thousands of animals and birds in a ritual sacrifice on Friday, ignoring calls by animal rights activists to halt what they described as the world's largest such exercise. (Photo by Navesh Chitrakar/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.

An orange oakleaf rests on a plant at the Taipei Zoo on November 26, 2020. (Photo by Sam Yeh/AFP Photo)

Marines finish a 10 kilometer training hike carrying 55 pound (25 kg) packs during Marine Combat Training (MCT) on February 22, 2013 at Camp Lejeune, North Carolina. Since 1988 all non-infantry enlisted male Marines have been required to complete 29 days of basic combat skills training at MCT after graduating from boot camp. MCT has been required for all enlisted female Marines since 1997. About six percent of enlisted Marines are female. (Photo by Scott Olson/AFP Photo)

“Attacking Howler Monkey”. Due to a major tropical rainstorm my wife and I were forced to stay overnight in a Howler Monkey Rescue center in Panama. I used the time to explore the area and to take photos of the monkeys. Just after the rain finally stopped, I ran into this monkey that tried to mock attack me. I quickly took a couple of photos before retreating to a (more) safe distance. (Photo and caption by Christian Mueller-Planitz/National Geographic Traveler Photo Contest)

ATTENTION! All pictures are presented in high resolution. To see Hi-Res images – just TWICE click on any picture. In other words, click small picture – opens the BIG picture. Click BIG picture – opens VERY BIG picture.

Krysten Ritter is seen at Sundance Festival on January 19, 2014 in Park City, Utah. (Photo by Alo Ceballos/GC Images)

This picture taken on March 1, 2016 shows a man running a mobile pig mating service and waiting outside a customer's home with his male pig in a cage pulled behind his motorcycle in the northern province of Bac Ninh. (Photo by Hoang Dinh Nam/AFP Photo)

This November 11, 2014 aerial photo, shows a deforested area dotted with blue tarps, marking the area where miners reside, and craters filled with water, caused by illegal gold mining activities, in La Pampa, in Peru's Madre de Dios region. Less than a month before Peru plays host to global climate talks, the government sent a battalion of police into southeastern jungles to dismantle illegal gold-mining mining camps. Peru's anti-illegal mining czar, retired army Gen. Augusto Soto, marched the men to the wasteland known as La Pampa, where 50,000 hectares of rainforest have been obliterated in the past six years. (Photo by Rodrigo Abd/AP Photo)