In the cinematic classic Wedding Crashers, Vince Vaughn and Owen Wilson blend seamlessly into nuptial bashes to score free crab cakes and to score with love-struck bridesmaids. When it comes to protest-crashing, the skilled, already well-known are the sign-wielding counter-demonstrators like the Protest Warriors scoring points with the Right. But what, I wondered, would it be like to slip into a lefty demonstration under the radar, à la Vaughn and Wilson, to see the lefties in their natural habitat, un-freaked by lingering righties? The only thing that made me hesitate before giving it a try was the fear that if...