A little girl hangs three Siamese kittens on a washing line in a garden in Croydon, London. (Photo by Fox Photos/Getty Images). 14th July 1931

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.

Eighty one-year-old Sakon Haba (L) wearing loin cloth walks past a police station after he bathed in ice-cold water at the Teppozu Inari shrine in Tokyo January 11, 2015. According to organizers, about 100 participants took part in the Shinto ceremony to purify their souls and wish for good health in the new year. (Photo by Toru Hanai/Reuters)

Pallas' s cat kittens with theit mother in an enclosure at the Novosibirsk Zoo, Novosibirsk, Russia on July 11, 2018. Pallas' s cat, also known as manul, is a small wild cat native to montane steppes of the Central Asia and listed as an endangered species. (Photo by Kirill Kukhmar/TASS)

A vendor carries her products in a bucket on her head as she walks through the neighborhood of Jalousie, in the commune of Petion Ville, Port-au-Prince, on December 17, 2018. On the hills of Port-au-Prince, a chaotic jumble of structures stretches ever farther into the distance: Haiti's capital is suffering under the weight of high inflation, endemic corruption and a perilous drop in the value of its currency. Jalousie is a poor neighborhood of the capital which lacks sanitation and potable water. (Photo by Hector Retamal/AFP Photo)

Dancers perform on stage during the Crazy Horse Paris “Forever Crazy” Media Call at The MasterCard Theatres at Marina Bay Sands on October 11, 2017 in Singapore. Forever Crazy consists of a series of highly aesthetic and visual tableaus presented by a classically trained dancers clad only in textured lighting and projection. The show runs from 11 October 2017 till 22 October 2017 in Singapore. (Photo by Suhaimi Abdullah/Getty Images)

Cosplayers dressed as She- Ra and Emma Frost pose for a photograph at the MCM Comic Con at ExCeL exhibition centre in London on October 28, 2017. (Photo by Tolga Akmen/AFP Photo)

His own space suit, with oxygen tank, doesn't make Barney the monkey any happier as he and actor Adam West view the situation in their space capsule in Hollywood on January 24, 1964. Barney, a South American woolly monkey, is blasted into space with West, as an astronaut, in a new movie, “Robinson Crusoe on Mars”. (Photo by AP Photo)