How’d that go viral? Snickers explains creepy Halloween ad that’s caught fire online

It’s an unsettling  commercial — perfect for Halloween. You’ve probably seen it: A mom confronts someone wearing a creepy mask in a grocery store aisle. The masked person is pushing Snickers on her; turns out it’s the mom’s kids behind the mask. The ad, from BBDO Worldwide, has gone viral. St. Louis’s  Riverfront Times spoke with a Snickers rep about the commercial. “We developed the dedicated Halloween spot as a creative way to remind moms that Snicker…