Kalei Ferrin,3, holds a sign up in support of gay rights during the San Diego gay pride parade July 16, 2011 in San Diego, California. About 200 active-duty troops and veterans from every branch of the military participated for the first time in the march as the ban on the government policy on homosexuals serving in armed forces, or “Don't ask Don't Tell”, remains in flux in the justice system. (Photo by Sandy Huffaker/Getty Images)

CANNES, FRANCE - NOVEMBER 03: Italian Prime Minister Silvio Berlusconi leaves the conference centre after the first day of the G20 Summit on November 3, 2011 in Cannes, France. World's top economic leaders are attending the G20 summit in Cannes on November 3rd and 4th, and are expected to debate current issues surrounding the global financial system in the hope of fending off a global recession and finding an answer to the Eurozone crisis. (Photo by Dan Kitwood/Getty Images)

“The Six-Day War or June War, also known as the 1967 Arab-Israeli War or the Third Arab-Israeli War, was fought between June 5 and June 10, 1967, by Israel and the neighboring states of Egypt (known then as the United Arab Republic [UAR]), Jordan, and Syria. The war began with a large-scale surprise air strike by Israel on Egypt. The outcome was a swift and decisive Israeli victory. Israel took effective control of the Gaza Strip and the Sinai Peninsula from Egypt, the West Bank and East Jerusalem from Jordan, and the Golan Heights from Syria. Opinions are divided on whether Israel's attack was an act of aggression or a preemptive strike of a defensive nature”. – Wikipedia

Photo: The corpse of a soldier lying on the line of the Israeli advance into Syria during the Six-Day War. (Photo by Terry Fincher/Getty Images). 1967

A humanoid robot named Kansei, meaning “sensibility” in Japanese, makes a facial expression depicting “happiness”, next to the word “Love” during a demonstration at a laboratory of Meiji University's Robot and Science Institute in Kawasaki, south of Tokyo in this June 4, 2007 file photo. Three-fourths of robot installations over the next decade are expected to be concentrated in four areas: transportation equipment, including the automotive sector; computer and electronic products; electrical equipment and machinery. Labor costs have climbed in countries such as China that have been popular for outsourcing production, while technological advances for robots allow them to be more flexible and perform more tasks. (Photo by Yuriko Nakao/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.

Aimee, 19, who has Down syndrome, has make-up applied by her mother before a presentation in Monterrey, Mexico, in this picture taken April 9, 2016. The association “Abrazame con Discapacidad” (“Embrace me with Disabilities”) teaches folk dance to low-income people with Down syndrome and manages presentations at public events where they receive a payment, as part of a therapy that helps improve their motor system, learning and self-esteem, the association said. (Photo by Daniel Becerril/Reuters)

“Hydrocynus goliath, also known as the goliath tigerfish, giant tigerfish or mbenga, is a very large African predatory freshwater fish. The giant tigerfish is restricted to the Zaire River system, Lualaba River, Lake Upemba and Lake Tanganyika”. (Photo by Tigerfishcamp / Tourettefishing / Bigfishesoftheworld)