Bottlenose dolphins swim over visitors in water tank at the Hakkeijima Sea Paradise aquarium-amusement park complex in Yokohama, southwest of Tokyo, Tuesday, July 21, 2015. Temperatures in Tokyo's metropolitan area neared around 96 degree Fahrenheit, or 35 degree Celsius, on Tuesday. (Photo by Shuji Kajiyama/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.

Films that are being screened are advertised in a makeshift cinema located under a bridge in the old quarters of Delhi, India May 25, 2016. A makeshift cinema hall under a 140-year-old bridge in the Indian capital is allowing poor rickshaw pullers and migrant labourers to escape daily hardship and sweltering heat into a world of Bollywood song, dance and romance. With the rusty iron floor of the bridge as its ceiling and some old rags acquired on the cheap from a nearby crematorium serving as curtains and floor mats, the cinema shows four films a day. (Photo by Cathal McNaughton/Reuters)

British model and UK Love Island's star India Reynolds attends the boohooMAN Dinner to celebrate the launch of BoohooMAN collaboration with Tommy Fury at Sushisamba City in London, England on September 2, 2019. (Photo by Splash News and Pictures)

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)

Family members perform the Manene traditional rite, cleaning the relatives' preserved remains, in Lembang on August 15, 2022, which is held every three years in August and is said to bless the harvest of rice fields. (Photo by Andri Saputra/AFP Photo)

A Kashmiri Shiite Muslim mourns as he flagellates himself during a Muharram procession in Srinagar, Indian controlled Kashmir, Thursday, July 27, 2023. Muharram is a month of mourning for Shiite Muslims in remembrance of the martyrdom of Imam Hussein, the grandson of the Prophet Muhammad. (Photo by Dar Yasin/AP Photo)

Elders perform coronation rituals on Kabaka (King) Ronald Muwenda Mutebi II during his 30 year coronation at his palace in Mengo, Kampala, on July 31, 2023. Thousands of Ugandans thronged the palace grounds of the country's largest kingdom Buganda despite pouring rain on July 31, 2023, dancing and ululating as they marked 30 years since the coronation of King Ronald Muwenda Mutebi II. (Photo by Badru Katumba/AFP Photo)