For its latest stunt, Improv Everywhere set up the 'Mannequin Mob,' which involved having people dress up in white suits and overwhelming the 5th Avenue Gap store in Manhattan with 50 extra mannequins.
Although we don't get to see it, there must have been a lot of prep work that went into this prank, because every fake mannequin was dressed in Gap clothes and totally fit in.
However, as Improv Everywhere is known to do, they caused a big scene. Since the human mannequins were instructed to freeze in place and had their faces covered, security wasn't too happy with the situation and called the police. In the end, all of the participants were left unscathed, (as well as without criminal records) although one participant was concerned that he wouldn't be able to use his gift card if he got banned from The Gap.