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 dressed up in a costume attends the 2021 Prague Comic Con in Prague, Czech Republic, October 16, 2021. (Photo by David W. Cerny/Reuters)

A man carries floats as he walks on an algae covered beach as a truck collecting algae passes by, along the coastline in Qingdao, Shandong province, July 6, 2015. (Photo by Reuters/China Daily)

People carry their pets before the start of a pet blessing at Greenhills shopping mall in Manila October 3, 2015. Pets were blessed on Saturday in a celebration honouring the patron saint of animals Saint Francis of Assisi. (Photo by Romeo Ranoco/Reuters)

Tourists take pictures of straw figurines of traditional deities Shennong (R) and Zhang Wulang (L back) during China's National Day Holiday, in Xinhua county, Hunan province, October 4, 2015. (Photo by Reuters/China Daily)

Costumed revellers walk in the streets of Lucerne during the annual carnival parade on Rose Monday March 3, 2014. (Photo by Sigi Tischler/AP Photo/Keystone)

“A huge wasp measuring 2.5 inches in length, visiting the banana tree in my front yard”. (Photo and comment by John Matzick, USA/2013 Sony World Photography Awards via The Atlantic)

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)