2016 Rio Olympics, Weightlifting, Final, Women's 63kg, Riocentro, Pavilion 2, Rio de Janeiro, Brazil on August 9, 2016. Marina Rodriguez (CUB) of Cuba competes. (Photo by Stoyan Nenov/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 photo made available on 14 March 2016 shows a Thai villager takes selfie photograph on drought parched land at the dried up Mae Chang reservoir in Lampang province, northern Thailand, 12 March 2016. The ruined village including ancient temple had been underwater for 34 years since the Mae Chang reservoir was built in 1982, the area has now re-emerged after water in the reservoir dried up caused by the severe drought. Thailand is facing the worst drought in decades hardest hit by El Nino phenomenon combined with seasonal hot weather. (Photo by Rungroj Yongrit/EPA)

French National Front party deputy Marion Marechal-Le Pen attends the questions to the government session at the National Assembly in Paris April 14, 2015. (Photo by Charles Platiau/Reuters)

Students rush past the bodies of inmates outside the Croix-des-Bouquets Civil Prison after an attempted breakout, in Port-au-Prince, Haiti, Thursday, February 25, 2021. At least seven people were killed and one injured on Thursday after eyewitnesses told The Associated Press that several inmates tried to escape from a prison in Haiti’s capital. (Photo by Dieu Nalio Chery/AP Photo)

Nature – first prize, stories. Pandemic Pigeons – A Love Story. The photographer’s daughter, Merel, cowers after Dollie flies past and perches on the balcony before entering the house in Vlaardingen in the Netherlands on 6 April 2020. “She’s still frightened when Dollie suddenly lands on the balcony railing. I hide my smile behind the camera, as I try to comfort her by saying they won’t hurt you. “I thought he was going to attack me”, she replies. As the nesting pigeons keep coming back to our place, slowly my girls have started to appreciate them – perhaps not as much as I do, but it’s a start”. (Photo by Jasper Doest/World Press Photo 2021)

Yana Shcherban of Russia looks at the ball after failing to receive it during their FIVB Women's Volleyball World Grand Prix 2014 final round against Japan in Tokyo August 20, 2014. (Photo by Yuya Shino/Reuters)

Syrian refugees sit behind barbed wire as they wait to cross into Macedonia at the Greek-Macedonian border, near the village of Idomeni, August 21, 2015. (Photo by Yannis Behrakis/Reuters)