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.

Yogis and street performers have been simulating levitation with nifty contraptions forever. They appear to be held aloft via nothing but their preternatural mental prowess. But are really enjoying the benefits of basic physics just like the rest of us when we use a chair. However, just because it’s perfectly explainable doesn’t mean it isn’t nifty. I’m especially impressed by this 2-person version and am still trying to work out how exactly the chair they’re using is shaped at the base.

A young man, who says he is part of a local criminal gang, poses for a picture holding a gun in the neighbourhood of Korogcho in Nairobi, Kenya, March 19, 2015. Around 2 million people live in the shantytowns packed in around Kenya's capital. Crime is high amid chronic unemployment levels, while basic services and sanitation are scarce. Residents try to make the best of things, eking out a living and picking up work where they can. (Photo by Siegfried Modola/Reuters)

Urszula Sidoruk, 19, from the paramilitary group SJS Strzelec (Shooters Association), trains her workout at a gym in Siedlce, eastern Poland March 18, 2014. Inspired by the war in Ukraine, growing numbers of Poles are joining volunteer paramilitary groups, where they receive basic army training and prepare to defend their homeland. (Photo by Kacper Pempel/Reuters)

Dutch artist Suzan Drummen‘s large-scale floor installations are mesmerizing and complex circular patterns made out of mirrors and brightly colored glass. The fractal-like arrangements feature ornate and elaborate circles growing exponentially out of each other and vibrant rings of spiraling colors winding into the surface of the floor. They are composed of crystals, chromed metal, precious stones, mirrors and optical glass. A sensory experience, and visually stimulating, the glittering installations play with the architecture of the space — climbing up walls and sweeping across the surfaces — examining the idea of illusion and optical effects.

A girl rides a donkey as another walks by at the Shawqaba camp for internally displaced people who were forced to leave their villages by the war in Yemen's northwestern province of Hajjah March 12, 2016. In northwest Yemen, one of the poorest countries in the Middle East, about 400 families uprooted by the war have been stuck in the Shawqaba camp in Hajjah province for the past year. Residents live in poorly built huts that protect them neither from summer heat nor winter cold in a camp that lacks the most basic services. (Photo by Abduljabbar Zeyad/Reuters)