With her bumbling mannerisms, bawdy language, and rambling conversations, the Nurse provides comic relief in several serious situations throughout "Romeo and Juliet." Shakespeare utilizes her character to provide amusement and action for the audience, especially the groundlings who would not be as interested in pure tragedy and verse as the more educated class would. So, in this most serious scene, the Nurse serves to not only accent the impetuous nature of youth, but provide some silliness for the audience that can probably recognize a relative of their own in the Nurse's character.
In Act 2, scene 5, Juliet is awaiting the Nurse's arrival with news from Romeo of whether or not he will marry her and, if he will, where and when the wedding will take place. By nature, Juliet, as well as Romeo, is extremely impatient and impetuous. Neither one of them waits to think about anything before he or she actually does it. This is one of the reasons Juliet is so impatient in this scene -- because it is a part of the characterization that Shakespeare has created for her. This scene actually shows how Juliet and the Nurse are foils of each other -- through the Nurse's patience and Juliet's impatience. A second, more easily accessible reason for her impatience is that she is waiting to find out if and when she will be married to the boy of her dreams.