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.

Brazilian graffiti artist Eduardo Kobra (C) puts the final touches to his piece of art in tribute to Brazilian architect Oscar Niemeyer, next to his assistants, at the financial center on Sao Paulo's Avenida Paulista January 22, 2013. Kobra created the 56-metre (61-yard) tall graffiti artwork as a tribute to Niemeyer, one of the 20th century's most influential modernist architects. Niemeyer died in December 2012, aged 104. (Photo by Andre Penner/AP Photo)

Tank crew standing in front of M-4 tank, Ft. Knox, Kentucky, June, 1942. (Alfred Palmer/OWI/LOC)

A girl carries utensils after filling them with water from a pipe that supplies water to trains at a railway station on the outskirts of Agartala, India, February 28, 2017. (Photo by Jayanta Dey/Reuters)

Pontoons, which were previously used as a floating jetty, are seen on the cracked ground of the Atibainha dam, part of the Cantareira reservoir, during a drought in Nazare Paulista, Sao Paulo state February 12, 2015. Brazil's worst drought in 80 years has left the Cantareira system, that provides greater Sao Paulo with most of its water, with the lowest water level on record. Brazil's economy is already expected to post zero growth this year. Worse yet, since Brazil depends on hydroelectric dams for about three quarters of its electricity, power shortages are also possible due to the drought, federal officials have said. (Photo by Paulo Whitaker/Reuters)

Have you ever tried painting with light? Yes, you’ve heard us right. It is not a figure of speech, and it is actually possible to draw with light if you have a good camera and a tripod. All you have to do is to set your camera on a tripod in a dark place (preferably at night in some park), set exposure time to the max, turn on a single bright light (the screen of your mobile phone will do), and you can start painting. Darren Pearson is a photographer who specializes in making such drawings. The level of intricacy with which he creates his paintings is astounding, considering the fact that making such a drawing is like painting with a blindfold on.

A statue is seen at the theme park “Love Land” on October 19, 2011 in Jeju, South Korea. Love Land is an outdoor sеx-themed sculpture park which opened in 2004 on Jeju Island. The park runs sеx education films and features 140 sculptures representing humans in various sеxual positions. It also has other elements such as large phallus statues, stone labia, and hands-on exhibits such as a “masturbation-cycle”. (Photo by James Jiao/Rex Features/Shutterstock)

Children with balloons play beside the statue of British comedy legend Eric Morecambe on January 16, 2012 in Morecambe, England. According to scientists January 16, 2012 was “Blue Monday”, the most depressing day of the year. (Photo by Christopher Furlong/Getty Images)