When the nurse looks for Romeo to deliver Juliet’s message of love, Mercutio immediately begins to mock her. She asks her servant Peter for a fan, and Mercutio makes fun of her looks: “Good Peter, to hide her face; for her fan's the fairer face.” He also offends the nurse (in spite of her fondness for sexual puns) by saying that it is evening rather than day because the “bawdy hand of the dial is now upon the prick of noon.”
Romeo jokes a little as well, but he also reveals that he is the one she seeks. Mercutio ridicules their liaison, calling her “a bawd” and singing about “An old hare hoar.” The nurse becomes extremely angry at this disrespect: “Now, afore God, I am so vexed, that every part about me quivers. Scurvy knave!” She says that she will beat him, and if she cannot, she will find those who will. Romeo attempts to smooth things over, dismissing Mercutio as “A gentleman, nurse, that loves to hear himself talk, and will speak more in a minute than he will stand to in a month.”
This scene shows that Romeo is better behaved than Mercutio. When Tybalt rankles at Romeo’s presence at the Capulet party, Lord Capulet chastises him, pointing to Romeo’s civil deportment. He tells Tybalt to leave Romeo alone, whom he says has a reputation as “a virtuous and well-govern'd youth.” Tybalt refuses to “endure him,” and Capulet loses his temper at Tybalt’s insolence, replying, “He shall be endured.” Romeo might be youthful and sometimes rash, but he does have some manners.
Mercutio makes fun of the nurse, angering her. Romeo treats her seriously and is respectful and gracious.
In Act I Scene 5, Capulet says of Romeo:
He bears him like a portly gentleman;
And, to say truth, Verona brags of him
To be a virtuous and well-govern'd youth:
I would not for the wealth of all the town
Here in my house do him disparagement:
Romeo demonstrates he is virtuous and a gentleman with his fair treatment of the Nurse.
Rome is seen as a gentleman and respects the Nurse while Mercutio is illmannered and makes sexual puns of the Nurse and doesn't respect her.