“The Lockheed SR-71 “Blackbird” was an advanced, long-range, Mach 3+ strategic reconnaissance aircraft. It was developed as a black project from the Lockheed A-12 reconnaissance aircraft in the 1960s by the Lockheed Skunk Works. Clarence “Kelly” Johnson was responsible for many of the design's innovative concepts. During reconnaissance missions the SR-71 operated at high speeds and altitudes to allow it to outrace threats. If a surface-to-air missile launch was detected, the standard evasive action was simply to accelerate and outrun the missile”. – Wikipedia

Photo: A U.S. Air Force SR-71A, also known as the “Blackbird”, is put through it's paces during a test flight over Beale Air Force Base in California. The aircraft is a strategic reconnaissance plane by Lockheed and is the world's fastest and highest flying operational aircraft. (Photo by Getty Images)

An officer wipes sweat off the face of a Chinese People's Liberation Army (PLA) honor guard soldier as they rehearse for a welcoming ceremony for New Zealand's Governor-General Sir Jerry Mateparae at the Great Hall of the People in Beijing, Tuesday, July 21, 2015. (Photo by Mark Schiefelbein/AP Photo)

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 Indian girl dressed in traditional attire reacts to camera as she watches a cultural performance during Lohri festival in Jammu, India, Monday, January 13, 2014. Lohri is a celebration of the winter solstice observed by Hindus and Sikhs in northern India. (Photo by Channi Anand/AP Photo)

Models present Victoria Secret Fantasy Bras priced at $2 million each during a media preview of the Singapore JewelFest in Singapore October 8, 2015. The festival which is in its 13th year, sees over 42 Asian designers participating and over $300 million worth of jewels for sale. It opens from October 9 to 18. (Photo by Edgar Su/Reuters)

In this June 1, 2016 photo, Maria Arias stands near her kitchen as she puts on earrings while getting ready for school in Caracas, Venezuela. So many students have fainted from hunger at Maria's school that administrators told parents to keep their children home until they could find more food. (Photo by Ariana Cubillos/AP Photo)

Early morning shark Sean McKeon pictured during severe flooding Oliver Plunkett street, Cork city, on February 3, 2014. (Photo by Daragh McSweeney/Provision)

South Korean football fans react during a public screening in Seoul of the South Korea vs Russia football match at the 2014 World Cup in Brazil, early on June 18, 2014. (Photo by Ed Jones/AFP Photo)