Man prepares wigs as he waits for customers in downtown Johannesburg, on August 5, 2014. Some estimates put Africa's dry hair industry at as much as $6 billion a year; Nigerian singer Muma Gee recently boasted that she spends 500,000 naira ($3,100) on a single hair piece made of 11 sets of human hair. (Photo by Siphiwe Sibeko/Reuters)

A fisherman throws his net beside a half-submerged M/V Palawan Pearl after it collided with a Cyprus-flagged BKM 104 dredger in Manila bay, Philippines on Thursday, July 8, 2021. A Philippine cargo vessel and a Cyprus-flagged dredger collided in a Manila Bay anchorage area early Thursday, resulting in no injuries but causing the cargo vessel to list and lie half-submerged in the busy waters. (Photo by Aaron Favila/AP Photo)

Khadija Amchichar, 12, and Amina Ouazzou, 8, react as they stand in a school turned into a shelter for displaced earthquake survivors, in the aftermath of a deadly earthquake, in the village of Outaghrri, Morocco on September 13, 2023. (Photo by Hannah McKay/Reuters)

Mount Whaleback iron ore mine 23°21’32.3”S, 119°40’40.1”E. The Mount Whaleback Iron Ore Mine in the Pilbara region of Western Australia. Roughly 98% of the world’s mined iron ore is used to make steel and is thus a significant component in the construction of buildings, automobiles, and appliances such as refrigerators. (Photo by Daily Overview/DigitalGlobe, a Maxar Company)

A devoteetakes a holy dip in the River Ganges on Ganga Dussehra festival in Prayagraj, India, Tuesday, May 30, 2023. Hindus across the country celebrate Ganga Dussehra by worshiping the River Ganges, which is considered as the most sacred and the holiest river. (Photo by Rajesh Kumar Singh/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.

A caiman in the Pantanal region of Brazil in 2021. They are used to seeing humans, allowing the photographer, Leighton Lum, a close-up shot. (Photo by Leighton Lum/Caters News Agency)

A man wades through flood waters carrying his grand daughter on his back following rains and floods during the monsoon season in Charsadda, Pakistan on August 28, 2022. (Photo by Fayaz AzizAziz/Reuters)