A pupil of the Dao ethnic tribe returns home from school along a hillside path at Suoi Thau village in Hoang Su Phi district of Vietnam's northern province of Ha Giang, located at the border with China, September 18, 2015. (Photo by Reuters/Kham)

A man jumps over a puddle outside Victoria Station, as heavy rain falls, in London, Monday June 20, 2016. Monday marks the Summer Solstice – the longest day of the year and the astronomical change of seasons when days are longest and nights are shortest in the Northern Hemisphere. (Photo by Lauren Hurley/PA Wire via AP Photo)

Penelope Cruz attends the Palme d'Or Award Ceremony held at the Palais des Festivals during the 63rd Annual Cannes Film Festival on May 23, 2010 in Cannes, France. (Photo by Sean Gallup/Getty Images)

Anja Rubik poses as she arrives for the screening of the film “Dolor Y Gloria (Pain and Glory)” at the 72nd edition of the Cannes Film Festival in Cannes, southern France, on May 17, 2019. (Photo by Stephane Mahe/Reuters)

Model Bella Hadid poses for photographers at the photo call for the film “Pain and Glory” at the 72nd international film festival, Cannes, southern France, Friday, May 17, 2019. (Photo by Arthur Mola/Invision/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 participant shows off a belt buckle during the 20th annual Seattle Invitationals, an amateur Elvis impersonator competition, in Seattle, Washington January 23, 2015. The event drew hundreds of spectators for 20 contestants at the Crocodile, a venue in Seattle's Belltown neighborhood. (Photo by David Ryder/Reuters)