When it comes to hockey, the Toronto Maple Leafs and the Montreal Habs are two of Canada's fiercest rivals. Heckling is a tradition, so in celebration of Canada's NHL season opener between MasterCard Canada -- a sponsor of both teams -- invited fans of each to submit their heckles via Twitter, Facebook or YouTube. An old-fashioned Barbershop Quarterset the heckles to a four part harmony, and recorded online videos (in both English and French) for each. Fifty-six original videos were shown on game day (October 1) over eight hours, and the campaign garnered 4.3 million Twitter impressions. MacLaren McCann was the agency responsible.