Interestingly, the Boston Massacre began with a snowball fight. On March 5, 1770, a gang of sixty Bostonians gathered outside the customs house and surrounded the British sentries standing guard. It wasn’t long until the tensions escalated to such an overwhelming level that, God help us, the colonists began to pelt the redcoats with snowballs. Not exactly your traditional brazen act of political rebellion.
What started as a schoolyard snow brawl, however, grew to something far more serious. One of the sentries fired a shot and it spurred the brutal gunfight that killed five colonists and served as a catalyst to the forthcoming American Revolution.
However significant, it was really more of a street fight than an actual massacre, at least by my standards. But colonial patriots such as the Sons of Liberty were quick to give the event the name by which it is now remembered. Big flashing titles like "massacre" inspire a lot more passion in a populace you're hoping to nudge towards revolution than less emphatic monikers do. The Boston Customs House Squabble? I think not.
Sources:
http://www.multied.com/revolt/Massacre.html
http://en.wikipedia.org/wiki/Boston_Massacre
And my faithful history textbook (Canada: A North American Nation by Bennet, Jeanen and Brune.)