In Act 2, Scene 4 of Romeo and Juliet, how does the Nurse provide comic relief?

In Act 2, Scene 4, Romeo’s friends make fun of Nurse and she teases Romeo.

Comic relief means that after a particularly dramatic moment, a character comes along that makes you laugh.  The nurse does this throughout the play, because she makes bawdy jokes and is just generally cheerful.  Also, other characters make fun of her occasionally.

Act 2, Scene 2 is a serious scene because Romeo and Juliet have professed their love for each other.  This is high drama in many ways.  First of all you have the, “ahh, that’s romantic,” touch.  Gushy romance goes a long way.  It’s also a little tense though, because Romeo and Juliet’s families are fighting!  They should not even be talking to each other, let alone kissing.  Uh, oh!  So that is dramatic, because although the audience might be enjoying the tender romance, if they have been paying attention they are also waiting for the other shoe to drop. 

There is a little humor in Act 2, Scene 3, where the friar chides Rome for going from one girl to the next, but it is mostly still dramatic.  He is reminding him of the consequences of his actions and Romeo is professing his love to be serious.

Enter nurse.  She is kind of bumbling and sweet, and tenderly devoted to Juliet but also a little bit obnoxious.  She is perfect comic relief, a typical Shakespeare clown.

In Act 2, Scene 4, Romeo’s friends make fun of Nurse (“A sail, a sail!”), and exchange bawdy conversation with her.  Romeo gets impatient with this conversation, answering thus when she asks for him:

I can tell you; but young Romeo will be older when
you have found him than he was when you sought him. I
am the youngest of that name, for fault of a worse. (Act 2, Scene 4)

Then, Romeo and the nurse exchange a witty conversation in which they tease each other.  She makes fun of the fact that he is impatient to hear from Juliet, and that Juliet is a sweet girl.  She also brings up Rosemary, the girl that he was supposedly in love with before.

NURSE:
…Doth not rosemary and Romeo begin both with a
letter?
ROM:
Ay, nurse; what of that? Both with an R.
NURSE:
Ah, mocker! that's the dog's name.  (Act 2, Scene 4)

Ultimately, she does tell him Juliet says yes, and arranges the meeting for him.  This little exchange is one of the humorous moments in the play, and there are some.  Mercutio also provides comic relief, and so does Romeo sometimes.

A play full of drama also needs some comedy.  Comedy and tragedy are two sides of the same coin, life is full of both.  Any play needs a fair amount of comic relief to give the audience some rest, and to balance out the tragic moments.  Shakespeare also wanted to keep his audience’s attention, and entertain them.  They would know whenever they saw Mercutio or the nurse (or a sword) that some fun was coming!

What are examples of comic relief between Romeo and the Nurse in Romeo and Juliet, Act 2, Scene 4?

In Act Two, Scene Four, the Nurse and her servant Peter come upon Mercutio, Benvolio, and Romeo in the street. Mercutio, as usual, has many witty things to say, but the nurse comes with a purpose:

Nurse: ...Gentlemen, can any of you tell me where I
may find the young Romeo?
Romeo: I can tell you; but young Romeo will be older when
you have found him than he was when you sought him:
I am the youngest of that name, for fault of a worse.

Romeo shows he can be witty, too, by remarking that since time has passed since she was looking for him, he is not as young as he was. This is in jest, since we wouldn't really consider someone to age in half a day.

Mercutio departs with Benvolio, and the nurse asks Romeo about him. Romeo says:

A gentleman, Nurse, that loves to hear himself talk, and will speak more in a minute than he will stand to in a month.

Romeo is picking fun at his friend, noting how Mercutio likes to hear the sound of his own voice and will talk nonsense just for fun. The Nurse also has quips with language, and is a match for Mercutio:

An he speak any thing against me, I’ll take him down, an he were lustier than he is, and twenty such Jacks. And if I cannot, I’ll find those that shall. Scurvy knave! I am none of his flirt-gills. I am none of his skains-mates.

Even when the nurse comes to the point of her seeking Romeo, we can find comedy in her language:

Pray you, sir, a word. And as I told you, my young lady bid me inquire you out. What she bade me say, I will keep to myself. But first let me tell ye, if ye should lead her into a fool’s paradise, as they say, it were a very gross kind of behavior, as they say. For the gentlewoman is young, and therefore, if you should deal double with her, truly it were an ill thing to be offered to any gentlewoman, and very weak dealing.

She says Juliet sent her to Romeo, but she will not repeat what Juliet asked her to say. This is rather silly, because then why did the nurse bother coming? She tells him that she wants to make sure his intentions with Juliet are honorable. Romeo begins to respond, and then she cuts him off:

Romeo: Nurse, commend me to thy lady and mistress. I
protest unto thee—
Nurse: Good heart, and, i' faith, I will tell her as much:
Lord, Lord, she will be a joyful woman.
Romeo: What wilt thou tell her, nurse? thou dost not mark me.
Nurse: I will tell her, sir, that you do protest; which, as
I take it, is a gentlemanlike offer.

While the nurse is seriously looking out for Juliet, and Romeo is genuinely assuring her of his affection for the girl, we can laugh at this exchange. The nurse gives a speech about how she wants to make sure Romeo will not hurt Juliet, and then all it takes is a few words from him, and she is assured. She says the fact that he protests the claim is enough to assure her.

They continue to joke with each other after it is settled that the nurse will help Juliet meet Romeo at Friar Lawrence's cell.

Nurse: Well, sir; my mistress is the sweetest lady—Lord,
Lord! when 'twas a little prating thing:—O, there
is a nobleman in town, one Paris, that would fain
lay knife aboard; but she, good soul, had as lief
see a toad, a very toad, as see him. I anger her
sometimes and tell her that Paris is the properer
man; but, I'll warrant you, when I say so, she looks
as pale as any clout in the versal world. Doth not
rosemary and Romeo begin both with a letter?
Romeo: Ay, nurse; what of that? both with an R.
Nurse: Ah. mocker! that's the dog's name; R is for
the—No; I know it begins with some other
letter:—and she hath the prettiest sententious of
it, of you and rosemary, that it would do you good
to hear it.

The actress playing the nurse can give a comedic delivery of how she is about to go on talking about how Juliet was young, and then switches to talking about Paris. Additionally, it is funny how the nurse says Juliet was a "prating thing," when the nurse herself would fit the definition of prating by talking foolishly at long lengths. She teases Romeo by telling him that she tells Juliet that Paris is better than Romeo.