Katie Handler, veterinary technician with the New England Wildlife Center, reaches to try to capture an oil-covered goose along the Muddy River, Monday, December 9, 2024, in Brookline, Mass., as wildlife rescuers tended to dozens of birds that were soaked in oil after an apparent spill. (Photo by Charles Krupa/AP Photo)

Austyn Scruggs, Alex Sutton and Josh Taylor, all sailors from NAS Jacksonville make their way down the 18th hole fairway in their St. Patrick's Day dragon costumes during the fourth and final round of The Players Championship PGA golf tournament at TPC Sawgrass in Ponte Vedra Beach, Fla. on March 17, 2024. (Phoot by Bob Self/Florida Times-Union via USA TODAY Network)

Hindu devotees, their bodies pierced with lemon and paladai, or bowl with a spout mainly used to feed milk to infants, wait to participate in a procession to mark Shivratri, or the night of Shiva, in Chennai, India, Wednesday, February 18, 2015. Such processions are held as an offering and show of devotion by devotees on the day dedicated to the worship of Lord Shiva, the Hindu god of destruction. (Photo by Arun Sankar K./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.

Children fill plastic containers with water from a well on a street, close to a neighbourhood called “The Tank” in the slum of Petare in Caracas, Venezuela, March 17, 2016. Although their nation has one of the world's biggest hydroelectric dams and vast rivers like the fabled Orinoco, Venezuelans are still suffering water and power cuts most days. The problems with stuttering services have escalated in the last few weeks: yet another headache for the OPEC nation's 30 million people already reeling from recession, the world's highest inflation rate, and scarcities of basic goods. President Nicolas Maduro blames a drought, while the opposition blames government incompetence. (Photo by Carlos Garcia Rawlins/Reuters)

Virgin Galactic's new spaceship N202VG (bottom L) is seen behind the WhiteKnightTwo carrier aircraft mothership (front), which landed safely after splitting from SpaceShipTwo, in a hangar at Mojave Air and Space Port in Mojave, California, November 4, 2014. (Photo by Lucy Nicholson/Reuters)

A picture released by the Italian Carabinieri on 03 July 2014 shows Carabinieri divers inspecting the inside of the Costa Concordia cruise ship, at Giglio Island, Italy, in 2012. The Costa Concordia hit a reef and partly capsized on 13 January 2012, after being steered dangerously close to Giglio, in an alleged stunt by captain Francesco Schettino. Thirty-two of the 4,229 people onboard were killed. (Photo by EPA/Carabinieri Press Office)

People look at a loaded truck that got stuck in a sinkhole on a road in Guilin, Guangxi Zhuang Autonomous Region, January 7, 2015. No injury was reported, according to local media. (Photo by Reuters/Stringer)