Don’t Think TwiceAre there people who don’t know what improvisational comedy is? Writer/director Mike Birbiglia seems to think so, because he begins his new film Don’t Think Twice with a short history of the development of improv and an explanation of the rules, the way each new onstage inspiration requires a “Yes, and … ” response from the other player in order to keep the sketch going. This primer makes the film stumble out of the gate, but all right, the rare individual who chooses to see a film about improv comedy without knowing how it works will be up to speed. Happily, the film does not feel the need to explain itself thereafter, and we are free to enjoy a pleasantly low-key comedy-drama credibly laced with disappointment and frustration—and the occasional onstage high.