Festivalgoers are seen running to the gates during the the first weekend of the Coachella Valley Music and Arts Festival at the Empire Polo Club on Friday, April 12, 2024, in Indio, Calif. (Photo by Amy Harris/Invision/AP Photo)

A male deer barks at dawn during the annual deer rutting season at Richmond Park in London, Britain, October 9, 2016. (Photo by Toby Melville/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.

A park ranger stands next to a nothern white female rhinoceros named Najin at Ol Pejeta Conservancy, some 290 kms north of the Kenyan capital, Nairobi, on January 27, 2015. Najin is one of only five members of the sub-species left on the planet, three of which reside at Ol Pejeta Conservancy. Conservationists and scientists met in Kenya this week to come up with a last ditch plan to save the northern white rhinoceros from extinction. (Photo by Tony Karumba/AFP Photo)

“Catch of the Decade”. Can you guess what happened next? Photo location: Katmai National Park, Alaska, USA. (Photo and caption by Aaron Baggenstos/National Geographic Photo Contest)

“My children are not only my little darlings but off-shoots of myself. When I look at them, I have a strange feeling – as if I am watching myself re-living my life. What I want to show is their “living form”. – Hideaki Hamada. Photo: “Rainy days and mondays #1”. (Photo and caption by Hideaki Hamada)

Corey Jurgensen runs along East Henry Avenue wearing an inflatable unicorn costume. Jurgensen has been wearing the costume during runs several times a week to cheer up others during this time of isolation but finds it therapeutic for herself as well to run through her Seminole Heights neighborhood wearing a silly costume, Thursday, April 16, 2020 in Tampa, Fla. (Photo by Martha Asencio Rhine/Tampa Bay Times via AP Photo)

Baloo (R), a North American Black Bear, rubs snouts with his companion Shere Hkhan, a Bengal tiger, inside their shared enclosure at Noah's Ark animal sanctuary in Locust Grove, Georgia, USA, 28 August 2014. According to the facility, the pair and a lion named Leo, were confiscated at a young age from a drug dealer's basement in Atlanta, Georgia. Noah's Ark cares for about 100 different species of animals on a 250 acre farm since 1990. (Photo by Erik S. Lesser/EPA)