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)

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.

“The Dragon and The Hopper”. Eyrean earless dragon (Tympanocryptis tetraporophora) standing tall on a very hot rock in western Queensland. For a short time it was joined by a hopper, who jumped off before becoming lunch. (Photo by Harrison Warne/Nature Conservancy Australia 2021 Photo Contest)

Gabriel Berendo, a businessman and car enthusiast, drives a casket converted into a car on Sunday May 31, 2020 in Cebu city, central Philippines as he goes around streets to remind residents to stay at home as lockdown measures to prevent the spread of the new coronavirus eases next week. (Photo by AP Photo/Stringer)

Specialist Dilip Patel, left, works at his post on the floor of the New York Stock Exchange, Monday, March 9, 2020. The Dow Jones Industrial Average sank 7.8%, its steepest drop since the financial crisis of 2008, as a free-fall in oil prices and worsening fears of fallout from the spreading coronavirus outbreak seize markets. (Photo by Richard Drew/AP Photo)

The Euro sculpture is partially reflected in a puddle on a cobblestone pavement in front of the headquarters of the European Central Bank in Frankfurt on Jan. 21. (Kai Pfaffenbach/Reuters)

During a jungle survival program February 20, 2013 taught by Royal Thai Special Forces in Sannapit, Thailand, U.S. Marines learned to catch cobras and drink their fresh blood, not to mention eat forest insects and pull the heads off of chicken. The training was part of Operation Cobra Gold 13, the 32nd edition of international military exercises hosted by the Thai. According to a U.S. Marines press release, Cobra Gold is the largest exercise of its kind in Asia and incorporates troops from five other nations in addition to the U.S. and Thailand. The Daily Mail reports that the Marines were invited to experience the local custom of drinking cobra blood after being taught to catch and kill cobras in the wild. As CNN notes, Cobra blood is believed to be a panacea and aphrodiasic in parts of Southeast Asia. In Jakarta, vendors can earn over $100 a night selling shots of cobra blood mixed with liquor. (Photo by Pornchai Kittiwongsakul/AFP Photo)

Competitors climb in front of the Matterhorn mountain at the start of the 21st Glacier Patrol race in Stafel outside the ski resort of Zermatt, Switzerland, 18 April 2018. The Glacier Patrol (Patrouille des Glaciers in French), organized by the Swiss Army, takes place from April 17 to 21. Highly-experienced hiker-skiers trek for over 53km (3994m ascent and 4090m descent) along the Haute Route along the Swiss-Italian border from Zermatt to Verbier. (Photo by Valentin Flauraud/EPA/EFE)