Flash mobs initially involved dancing in the streets, freezing like statues or even giant pillow fights.
But then something else happened. Bicyclists in San Francisco and Los Angeles started blocking traffic to protest lack of respect from motorists. A spontaneous snowball fight during the winter's epic snowstorm in Washington, D.C., went sour when a plainclothes policeman pulled out a gun.
And, then, two weeks ago in Philadelphia, touristy South Street was the scene of a flash mob gone bad....Full Story