"Of course it's difficult to turn anything down when Mike Nichols calls you personally"

This quote by Andrea Martin is referring to the experience of being asked to work with the famous director Mike Nichols. Nichols was an extremely well-known director, producer, and author, and his films have won many awards. As such, it is easy to understand that Martin would feel honored to be personally asked by him to deal with a job. The quote indicates that it would be hard to turn down such a deal, as it is a rare opportunity to deal with a master of the craft. It also suggests that Nichols was a personable person, as he made the effort to call Martin personally. This quote talks to the respect and adoration that Martin had for Nichols, and the difficulty of denying such a deal.