Large trumpet vines spread across electrical lines next to a highway in Kinston, N.C., on June 23, 2014. (Photo by Janet S. Carter/Kinston Free Press via AP Photo)

Russian servicewomen march at Red Square during the Victory Day military parade in Moscow on May 9, 2017. Russia marks the 72nd anniversary of the Soviet Union's victory over Nazi Germany in World War Two. (Photo by Kirill Kudryavtsev/AFP 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.

A military band playing during the Immortal Regiment march in Vladivostok, Russia on May 9, 2016. The celebrations marked the 71st anniversary of the defeat of Germany in WWII. (Photo by Yuri Smityuk/TASS/Getty Images)

A fisherman with a close bond to cormorants uses the flock of birds to catch big fish in Li river in Guilin, China. The aquatic birds can be seen perching on a bamboo raft before swooping into the calm water to grasp hold of prey. (Photo by Julia Wimmerlin/Solnet News & Photo Agency)

A woman wearing a face mask to help protect against the spread of the new coronavirus crosses a stream in Seoul, South Korea, Wednesday, July 15, 2020. (Photo by Lee Jin-man/AP Photo)

Santa Claus wears a mask as he pushes a sleigh full of curbside grocery orders to an Aldi customer at a parking lot in Palatine, Ill., Saturday, December 19, 2020. For this weekend only, Santa Claus is delivering groceries to Aldi customers in Palatine and several other towns in the Chicago area. (Photo by Nam Y. Huh/AP Photo)

A man shows his inked finger after casting his ballot at a polling station during the second phase of voting of India's general elections in Masuda, Rajasthan state, on April 26, 2024. (Photo by Himanshu Sharma/AFP Photo)