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.

Apple CEO Tim Cook discusses the new iPhone 6 and iPhone 6 plus on Tuesday, September 9, 2014, in Cupertino, Calif. The iPhone 6 will have a screen measuring 4.7 inches, while the iPhone 6 Plus will be 5.5 inches. (Photo by Marcio Jose Sanchez/AP Photo)

“Coming back home at 5am sunrise, I was just beginning to digest the grand event I was lucky to witness and cover: the wedding of the grandson of one of the most influential spiritual leaders in Israel’s ultra-Orthodox community...”. – Ronen Zvulun via Reuters. Photo: Ultra-orthodox Jewish wedding in Israel. Tens of thousands of Ultra-Orthodox Jews of the Belz Hasidic dynasty gather at the wedding ceremony of Rabbi Shalom Rokach in Kiryat Belz, in Jerusalem, on May 21, 2013. Around 25,000 ultra-orthodox Jews took part, making it one of the biggest weddings of the past few years. (Photo by Gil Cohen)

This picture taken on January 25, 2015 shows a participant taking part in an ice water challenge in Zhangjiajie, central China's Hunan province. Participants were required to stay in an ice pond, holding an ice block while eating ice-cream with an electric fan blowing at them. (Photo by AFP Photo/Stringer)

Smoke rises during an explosion from an Israeli forces strike in Gaza City, Saturday, November 17, 2012. Israel bombarded the Hamas-ruled Gaza Strip with nearly 200 airstrikes early Saturday, the military said, widening a blistering assault on Gaza rocket operations by militants to include the prime minister's headquarters, a police compound and a vast network of smuggling tunnels. (Photo Hatem Moussa/AP Photo)

Archie, a Chinese Crested dog, sits with his tongue out before the start of the 20th Annual Ugliest Dog Competition at the Sonoma-Marin Fair June 20, 2008 in Petaluma, California. Owners of ugly dogs travel to Petaluma from all over the country to participate in the annual contest. (Photo by Justin Sullivan/Getty Images)

David Guttenfelder was born in Iowa and graduated from the University of Iowa with a Bachelor of Arts in cultural anthropology. He has worked for the AP since 1994 based in Kenya, the Ivory Coast, India and Japan. He is currently AP’s chief Asia photographer and his feature work has been used prominently in editorial publications throughout the world including Time and National Geographic. Photo: U.S. soldiers from the 2nd Battalion, 12th Infantry Regiment, 4th Brigade Combat Team, fire mortars at known enemy firing positions from a base in the Pech River Valley in Afghanistan's Kunar province, Saturday, October 24, 2009. (Photo by David Guttenfelder/AP Photo)

Kumari Samita Bajracharya sits in front of devotees offers during a special puja at Kumari Ghar in Patan, Nepal, 09 April 2011. It is believed that worshipping Kumari and receiving tika from her reduces illness and avoid problems. Kumari, or Kumari Devi, is a “living goddess”. The word literally means virgin in Nepali. The Living Goddesses are young pre-pubescent girls that are considered to be incarnations of the Hindu Goddess of Power, Kali. The Kumari retires when she reaches puberty. (Photo by Narendra Shrestha/EPA)