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 female street art collective has set a new Guinness World Record to create the largest spray-painted mural by multiple artists. Over 100 international female street artists came together to create the continuous mural in south London’s Leake Street Tunnel, made famous by Banksy, on March 8, 2014. The record was broken as part of all-female street art event Femme Fierce, the largest of its kind in the UK, which aims to celebrate women street artists across the world. Photo: Zabou's witty graffiti. (Photo by Dez Mighty/Susan Mackey)

An Afghan policeman frisks a man while a burqa-cald woman sits in the trunk of a car on a roadside in Herat, Afghanistan, 05 July 2015. At least 18 police, two civilians and 30 rebels were killed in central Afghanistan during three days of fierce fighting, police said on 04 July. The clashes ended 04 July after security forces retook control of nine police checkpoints that had fallen to the rebels. (Photo by Jalil Rezayee/EPA)

Arrow sports his new elastic booties at a PetSmart in Tempe, Ariz. on Tuesday, June 20, 2017. Phoenix radio station KSLX handed out the protective coverings to protect dogs' paws from the hot pavement, as temperatures in Phoenix are forecasted to hit 120 degrees (48°C). (Photo by Angie Wang/AP Photo)

Biologist Kelly Martin records her measurements of Electra, a 5 1/2 foot leatherback turtle nesting on the beach behind the Seminole Golf Club course in Juno Beach. Martin uses a red light which is invisible to turtles. (Photo by Greg Lovett/The Palm Beach Post)

India: A sweeper cleans the side of a road near a replica of the Eiffel Tower amid heavy fog in the early morning in the northern Indian city of Chandigarh January 18, 2010. (Photo by Ajay Verma/Reuters)

Frog legs it! Indonesian flying frog tries to hitch a ride on snail's back before realising it would be quicker to hop it alone. A tiny frog struck up an unlikely friendship with a giant African land snail after clambering onto its shell to catch a ride. (Photo by Hendy Mp/SOLENT/Visual Press Agency)