Customers bag their purchases as employees scan items at a checkout counter inside an Asda supermarket, operated by Wal-Mart Stores Inc., in the Wembley district of London, U.K., on Friday, Nov. 28, 2014. Black Friday has caught on in the U.K. and worldwide over the last few years as the rise of the Internet has made the event a global phenomenon, with customers always being just one click away from the deals offered by U.S. retailers online. Photographer: Simon Dawson/Bloomberg via Getty Images