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 reveller dressed as Spider-Man takes part in a presentation at the top of a building during an annual block party known as “Enquanto isso na Sala da Justiça” (Meanwhile, in the justice room), one of the many carnival parties taking place in the neighbourhood of Olinda, Brazil February 7, 2016. (Photo by Ueslei Marcelino/Reuters)

A protester from the People for the Ethical Treatment of Animals (PETA) displays a placard from a bathtub as a people looks on during a demonstration to call on the public to eat more vegetables to save water, in Sao Paulo on August 2, 2016. (Photo by Cris Faga via ZUMA Wire)

Gertrude “Billie” Murphy, 22, is brought in for questioning in the murder case of Michael Stopec, who was shot and killed in an apartment hotel, circa July 1927. Murphy had been friends of the married Stopec and his suspected killer Henry Guardino, 31. It is said that Stopec and Guardino were “bitter rivals for the favor of Billie” and that Murphy had tired of Guardino and was going to stay with Stopec. Murphy was also married to a man in the Joliet penitentiary. (Photo by Chicago Herald & Examiner Historical Photo)

Sculptured figures titled “Huck and Jim” is on display at a press preview at The Met Fifth Avenue in New York City on Monday, January 24, 2022. (Photo by John Angelillo/UPI/Alamy Live News)

Arcelia Aguilar, a resident of “Hogar Jardin De Los Abuelitos”, receives a hug from her niece Maria Aguilar through “El muro de los Abrazos” (The Wall of Hugs) which is a wall made from plastic sheets to protect against the coronavirus, in San Salvador, El Salvador on September 1, 2020. (Photo by Jose Cabezas/Reuters)

Artists perform during a “Yandu Story” Show performance, in Yancheng, Jiangsu province, China, 20 September 2022. The story dates back to some 100 years when – according to the organizers – two prominent local families, Gu and Ling, were committed to get out of a predicament, but parted due to different development concepts and ended in a turmoil. The large-scale immersive series of performances took more than a year of careful planning and consists of two parts: a daytime performance and a 90-minute night performance, they added. (Photo by Alex Plavevski/EPA/EFE/Rex Features/Shutterstock)

Spain's acting acting Minister of Labor and Sumar MP Yolanda Diaz (Front-C) takes her seat at the Lower House in Madrid as they attend the Constitutive Session of the Lower House for the 15th legislature in Madrid, Spain, 17 August 2023. The Upper and Lower chambers celebrate their Constitutive Session for the 15th legislature after the general elections that took place last 23 July 2023. (Photo by Juan Carlos Hidalgo/EPA)