This is what it is all about, he knows: improbability. It is the joke that this whole circus is built around: a tiger, an elephant, a hot air balloon, right here in Des Moines or Indianapolis or Altoona. Seven clowns and a monkey piling out of a car, one after the other in a tangle of funny shoes and makeup and hobo clothes, and just when you think there surely couldn’t be more room in that car, here comes another one.