Chad Rowley and his wife Susan race during the 22nd North American Wife Carrying Championship at Sunday River Resort in Newry, Maine, on October 9, 2021. Couples compete on a 278-yard (254-meter) obstacle course for a prize of wife's weight in beer and five times her weight in money. Winners are invited to the world championship in Finland where the sport originated. (Photo by Joseph Prezioso/AFP Photo)

A racoon jumps over a fence in almost deserted Central Park in Manhattan on April 16, 2020 in New York City. Gone are the softball games, horse-drawn carriages and hordes of tourists. In their place, pronounced birdsong, solitary walks and renewed appreciation for Central Park's beauty during New York's coronavirus lockdown. The 843-acre (341-hectare) park – arguably the world's most famous urban green space – normally bustles with human activity as winter turns to spring, but this year due to Covid-19 it's the wildlife that is coming out to play. (Photo by Johannes Eisele/AFP Photo)

A woman carries a stone cross in a cemetery in the village of Copaciu, southern Romania, on May 2, 2013. As part of a Holy Week tradition, Romanians visit, on Maundy Thursday, the graves of their loved ones, light fires and share food with community members in memory of the departed. Orthodox worshipers celebrate Easter on May 5. (Photo by Andreea Alexandru/ Mediafax)

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.

This photo taken on August 7, 2016 shows mahjong enthusiasts playing mahjong under water in a swimming pool at a diving club in the Chinese city of Chongqing. Only participants with proper diving certification were allowed to take part in the underwater competition. (Photo by AFP Photo/Stringer)

Alex Plunkett, left, and Sean Hart, both of Arlington, Va., join hundreds participating in the annual International Pillow Fight Day on April 5. Massive pillow fights broke out on the Mall in Washington and in cities around the world. (Photo by Marvin Joseph/The Washington Post)

Fans of the Kansas City Chiefs pose for photos before the game against the Los Angeles Chargers at Estadio Azteca on November 18, 2019 in Mexico City, Mexico. (Photo by Manuel Velasquez/Getty Images)

Meghan Puhr participates in a virtual realty presentation during an Intel news conference before CES International, Wednesday, January 4, 2017, in Las Vegas. (Photo by John Locher/AP Photo)