Several beaches along South Florida's Atlantic coast line were closed after thousands of sharks were seen migrating in the waters. The sharks were migrating from Boca Raton to Jupiter since the beginning of March, marine biologists told NBC Miami. Photo: A spinner shark swims just offshore on Midtown Beach in Palm Beach on Tuesday. (Photo by Jeffrey Langlois/Palm Beach Daily News)

Armed Syrian Turkmen villagers are seen near the northern Syrian village of Yamadi, near the Turkish-Syrian border, Syria, November 24, 2015. Turkey shot down a Russian warplane near the Syrian border on Tuesday saying it had repeatedly violated its air space, one of the most serious publicly acknowledged clashes between a NATO member country and Russia for half a century. (Photo by Reuters/Stringer)

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 Naga sadhu, or naked Hindu holy man, performs a ritual inside his tent during Kumbh Mela, or Pitcher festival, at Trimbakeshwar, India, Friday, August 28, 2015. Hindus believe taking a dip in the waters of a holy river during the festival will cleanse them of their sins. The festival is held four times every 12 years. (Photo by Rajanish Kakade/AP Photo)

Women blow coloured power during Holi celebrations in Chennai, India, March 10, 2020. Holi is observed in India at the end of the winter season on the last full moon of the lunar month. (Photo by P. Ravikumar/Reuters)

A dragster supercharger hits cameraman Joe Rooks of Bowling Green, Ohio, in the back at the U.S. Nationals N.H.R.A. drag races in Indianapolis, Indiana, on Saturday, September 1, 1979. Rooks was knocked flat by the heavy blower from a dragster that turned over and disintegrated near Rooks. Rooks died en route to the hospital. (Photo by Chuck Robinson/AP Photo)

Long-tailed mayflies (Palingenia longicauda) at Tisza river near Tiszainoka 135km (84 miles) southeast of Budapest, June 23, 2013. Millions of these short-lived mayflies engage in a frantic rush to mate and reproduce before they perish in just a few hours during “Tiszaviragzas” or Tisza blooming season from late spring to early summer every year. (Photo by Laszlo Balogh/Reuters)

A traveller washes his horse in the River Eden in preparation for selling at the Appleby Horse Fair on June 3, 2011 in Appleby, England. Appleby Horse Fair has existed under the protection of a charter granted by James II since 1685. It is one of the key gathering points for the Romany, gypsy and traveling community. Appleby Horse Fair is attended by about 5,000 travelers who come to buy and sell horses. The animals are washed and groomed before being ridden at high speed along the “mad mile” for the viewing of potential buyers. (Photo by Christopher Furlong/Getty Images)