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)

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

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.

Actress Kaitlyn Leeb poses in front of the “Total Recall” display as the three breasted woman in the Sony booth on Day 2 of Comic-Con International 2012 held at San Diego Convention Center on July 12, 2012 in San Diego, California. (Photo by Splash News and Pictures)

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)

Indian mourners perform a cremation on the roof of a building overlooking The Manikarnika Ghat in Varanasi on August 23, 2016. India's holy city of Varanasi has been forced to halt cremations along the banks of the sacred river Ganges as deadly floods from monsoon rains hit parts of the country, an official said. More than 100,000 people have been forced from their homes in recent days in northern Uttar Pradesh and neighbouring Bihar states as rain-swollen rivers burst their banks. (Photo by Sanjay Kanojia/AFP Photo)

A priest is seen looking out of Abuna Yemata church’s only window. Priests cheerfully tell visitors that pregnant women, babies and old people attend Sunday services and no one has fallen off. (Photo by Ethiopia – The Living Churches of an Ancient Kingdom/The American University in Cairo Press/The Guardian)