In "Romeo and Juliet," why does Mercutio make fun of Romeo after they leave the party?
In act 2, scene 1, Benvolio and Mercutio search for Romeo, who has climbed over the orchard wall to see Juliet. Mercutio is completely unaware that Romeo has fallen for Juliet and is still under the impression that Romeo is lovesick over Rosaline. Mercutio, who is a witty skeptic, makes fun of Romeo by demanding that he show himself in the name of Rosaline. Mercutio then proceeds to make crude sexual jokes directed at Romeo, hoping that Romeo will respond to his derogatory remarks. However, Romeo does not show and waits outside of Juliet's balcony. Overall, the reason Mercutio makes fun of Romeo is because he wants Romeo to reveal himself. Mercutio is also a rather callous man and thinks that Romeo is overreacting about Rosaline's unrequited love. He believes that Romeo needs to stop acting depressed and cheer up because he is young, wealthy, and attractive, which is why he makes fun of him when he is not present.
The primary reason Mercutio makes fun of Romeo is because he has a strong feeling Romeo is hiding nearby and means to lure him out by insulting him. Not having witnessed Romeo's dance with Juliet, Mercutio believes that nothing has changed in the last hour or so and that Romeo is still in love with Rosaline. Mercutio mocks Romeo's feelings for Rosaline, letting us know that not only does he think Romeo is a fool for falling in love, but he does not think falling in love is respectable.
Romeo does overhear these jibes and, even though he no longer cares for Rosaline and has fallen in love with Juliet, the words still upset him, because he knows that Mercutio will not understand his feelings for Juliet. Therefore, Romeo decides to remain hidden and not confide in his friend.
After the "masquers" leave the Capulet party, Romeo among them, Romeo leaps an orchard wall and hides. Mercutio teases Romeo with crass sexual humor in an attempt to get Romeo to emerge from his hiding place. Ironically, Mercutio's humor focuses on Rosaline, while Romeo has already forgotten Rosaline and fallen in love with Juliet.