What is the long horn used at hockey games?

Answer 1

I believe that you are referring to the vuvuzela. It gained much of its popularity(or at least notoriety) at the 2010 FIFA World Cup. The vuvuzela has been a standard figure South African football(soccer) matches, and they came out in force at the World Cup(with much controversy).

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Most of the horns are air horns, not vuvuzela. Most arenas in Canada have actually banned vuvuzelas. You can't even take them to soccer games because they get confiscated.