That which we call a fad by any other name would work as well
So London plans to celebrate the Olympics this summer by having actors accost unsuspecting pedestrians and recite Shakespeare at them. (e.g., "Good Mistress Accost, I desire better acquaintance!") (H/T You've Cott Mail. No kidding: if you don't subscribe to Thomas Cott, you don't know what's going on in the arts world. Or, as it is written, if you don't get it, you don't get it.)
Meanwhile, Danish musicians orchestrate (what else would they do?) an art attack on Copenhagen's Central Station.
Maybe only Scandinavians have the sang-froid to perform Ravel's Bolero in public with a straight face (10, anyone?), but Chicago Opera Theater celebrated the start of November by sending four of its singers to surprise commuters at the French Market in the Metra Station.
So pop-up performances (like pop-up art galleries) are something of a fad, and easy to dismiss for that reason. But they're also the embodiment of the idea that we have to take our art to the people instead of expecting them always to come to us.
So how about it? If London can celebrate the presence of the Olympics, why can't Chicago celebrate their absence? We have plenty of fine Shakespearean actors, if Shakespeare's the thing. Or--better yet--some woman on the bus turns to you and announces, "Attention must be paid!" or "I have always depended on the kindness of strangers." (That should go over big.)
Chicago hasn't had a really kick-ass public art event since the Cows, and that was a dozen years ago, already. So, theater artists, what do you say? Don't let the visual artists have all the glory! Pop up somewhere and show us what you can do!