A woman tour skates on the frozen lake of Orlangen, south of Stockholm, Sweden, on December 23, 2016. Tour skating is recreational long distance ice skating on natural ice particularly popular in the Nordic countries. (Photo by Tobias Roestlund/AFP Photo/TT News Agency)

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.

Men transport a sheep on their motorcycle after buying it at an old cattle market named “Al Emam Market” ahead of the Muslim festival Eid al-Adha in Cairo, Egypt, September 19, 2015. Muslims across the world are preparing to celebrate the annual festival of Eid al-Adha or the Festival of Sacrifice, which marks the end of the annual hajj pilgrimage, by slaughtering goats, sheep, cows and camels in commemoration of the Prophet Abraham's readiness to sacrifice his son to show obedience to Allah. (Photo by Amr Abdallah Dalsh/Reuters)

Amateur astronomer Bill Snyder has been involved with astrophotography since 2007. Photo: The Cygnus Wall is in the southern area of NGC7000 also known as the North America Nebula. It is approximately 1800 light years from Earth, and is in the constellation Cygnus. The Wall is an energized shock front and contains the most concentrated star formations in the nebula. The size of the North America Nebula is about 4 full moons. (Photo and caption by Bill Snyder)

A racegoers walks into a rubbish bin following 2016 Melbourne Cup Day at Flemington Racecourse on November 1, 2016 in Melbourne, Australia. (Photo by Scott Barbour/Getty Images)

A Vietnamese woman collects dried incense sticks at a courtyard in Quang Phu Cau village on the outskirts of Hanoi on January 9, 2020 ahead of the upcoming Lunar New Year celebrations, referred to in Vietnam as Tet. (Photo by Manan Vatsyayana/AFP Photo)

Russian Il-76 military transport aircrafts fly in formation during a rehearsal for the flypast, which marks the 75th anniversary of the victory over Nazi Germany in World War Two, in Moscow, Russia on May 4, 2020. The traditional large-scale Victory Day military parade across Red Square was postponed due to the outbreak of the coronavirus disease (COVID 19). (Photo by Maxim Shemetov/Reuters)

Firefighters use a rope to rescue a group of people stranded in a flooded street on July 12, 2018 in Chengdu, Sichuan Province of China. A strong storm has hit many parts of southwest China's Sichuan Province since Monday, causing landslides and floods in the region. (Photo by Wang Hongqiang/Chengdu Economic Daily/VCG)