A serviceman of Russia's Emergencies Ministry wearing protective gear disinfects Moscow's Leningradsky railway station on May 19, 2020, amid the COVID-19 coronavirus pandemic. (Photo by Kirill Kudryavtsev/AFP Photo)

John Pfaff lays on a fallen tree Thursday, September 10, 2020, in Salt Lake City. Two days after a windstorm wreaked havoc in Utah, many schools remain closed and tens of thousands are still without power. (Photo by Rick Bowmer/AP Photo)

Protesters carry a giant old Belarusian national flag during a Belarusian opposition supporters' rally protesting the official presidential election results in Minsk, Belarus, Sunday, September 13, 2020. Belarusians have been demonstrating against the disputed re-election of President Alexander Lukashenko for a month, with more than 100,000 people flooding the streets of Minsk for four straight weekends. (Photo by TUT.by via AP Photo)

Pals let their hair down for one last hoorah in Cardiff, capital of Wales on September 12, 2020. Groups of friends crammed into pubs and restaurants to “go out in style” before the “rule of six” is enforced on Monday. (Photo by Huw Evans Picture Agency/The Sun)

Faithful wearing face mask pray during the Arafah prayer ceremony ahead of Eid al-Adha, at the Tehran university’s mosque in Tehran, Iran, 30 July 2020. Iran will not hold the Eid al-Adha prayers and ceremonies over the coronavirus (COVID-19) crisis in the country. (Photo by Abedin Taherkenareh/EPA/EFE)

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.

Crocodile meat parts stands on display on Huangsha Seafood Market in Guangzhou, Guandong Province, China, 20 January 2018. Tsukiji Market of China or Huangsha Seafood Market is biggest one in Southern China and one of the biggest in China, as there are literally hundreds of different varieties of fish and seafood scattered throughout the market. (Photo by Aleksandar Plavevski/EPA/EFE)

Brides display their hands decorated with henna around a bride as she poses for her own photographer during a mass marriage ceremony in which, according to its organizers, 70 Muslim couples took their wedding vows, in Ahmedabad, India, February 11, 2018. (Photo by Amit Dave/Reuters)