Anyone who's seen improv comedy can attest to its fast-paced spontaneity, but everything can change in the blink of an eye. In only a second, a joke may fall flat or go on for too long, a performer might introduce a new element to the joke or maybe a suggestion is just plain odd. However, the performers of Mile High Comedy Theater, Prescott's resident improvisational and standup sketch comedy group, know just how to keep their heads when the difference between a room of dead silence and a crowd roaring with laughter is a matter of only seconds.Related story: Laugh it up at Mile High Comedy show Friday.