A Pakistani farmer guides his bulls as he competes in a traditional bull race in Khunda village in the northwestern district of Attock, some 80 kilometers from Islamabad on January 3, 2015. Tens of thousands of people gather whenever there is a bull race held in Pakistan which are usually the highlight of festivals organized in rural areas of the Asian country, and attract lots of spectators due to their thrilling nature. The traditional competition attracts landlords and farmers from all around the province where the race is held, and they all bring their fastest and strongest bulls in hopes of gaining a reputation. (Photo by Aamir Qureshi/AFP Photo)

A man washes his horse as a woman bathes her son at concrete water pens under a flyover in a slum area in Kolkata, India October 21, 2016. (Photo by Rupak De Chowdhuri/Reuters)

Nadeea Volianova the Russian Pop Star's bizarre, naked New Years “Art Installation” featuring an American flag, the named Putin and Trump in huge letters and the singer wearing a space helmet and not much else, Art Threat Gallery, Las Vegas, NV on December 29, 2016. (Photo by S_bukley/Splash News and Pictures)

A Muslim man carries holy incensed smoke through a pedestrian subway in Mumbai, India, May 13, 2016. (Photo by Danish Siddiqui/Reuters)

The sanctuary of Lourdes flooded, in Lourdes, southwestern France, Tuesday, June 18, 2013. French rescue services and police are evacuating hundreds of pilgrims from hotels threatened by floodwaters from a rain-swollen river in the Roman Catholic shrine town of Lourdes. (Photo by Bob Edme/AP Photo)

Star Wars enthusiasts wear costumes resembling what they say are three “Chew's Angels” during the 2015 Comic-Con International Convention in San Diego, California July 10, 2015. (Photo by Mario Anzuoni/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 aerial view shows the 11/19 pit and twin slag heaps at the former coal mine site in Loos-en-Gohelle, northern France, November 1, 2015. Loos-en-Gohelle, a town of 7000 inhabitants in the North of France, marked by the closure of coal mines in 1970, has demonstrated a successful transition from coal to a green economy. (Photo by Pascal Rossignol/Reuters)