Potential sign caption:
“Purple is the new brown”
(Although I doubt the average SEIU cretin would get it).
However, the general tactic remains - when facing overwhelming numbers of well-organized robots, jiu-jitsu is the way to go - use their own strength against them.
Maybe the following would make for a better sign: “Brown shirt, Purple shirt - what’s the difference?” or “Brown shirt, Purple shirt - there is no difference”.
Local tea party's might try to get some marine VETERANS to be hanging around at the next confontation.
Those folks know how to intimidate, verbally and physically.
If someone touches you, it's assault, isn't it?
SEIU = SOW (and call 'em that)
PURPLE SHIRT = BROWNSHIRT (I bet if you mix yellow and purple, you get BROWN !)