Customers push loaded shopping carts through crowded aisles as they look for bargains during a Black Friday discount sale inside an Asda supermarket in Wembley, London, U.K., on Friday, Nov. 29, 2013. Britons queued outside Asda supermarkets this morning and charged into stores when doors opened at 8 a.m. as the U.K. grocery chain took on the Black Friday mantle from U.S. owner Wal-Mart Stores Inc. Photographer: Simon Dawson/Bloomberg via Getty Images