Someone pulls the strings. There have been riots at some flash mobs.
It also provides a bunch of bodies to “mount a large protest” (even if the sheep don’t know it IS a protest being staged for cameras).
It also provides potential cover (or targets) for a planned terrorist strike.
But everybody ELSE is doing it so by all means, go where some anarchist somewhere says to go at “3:25pm” today...
That is exactly what I have been thinking.
My worst fear is that a flash mob will be called to an area where some Islamofascists have pre-planted some car bombs.