What scenes are used for comic relief in the story?

Mercutio and Nurse both provide comic relief throughout the play. Both tend to be bawdy..... Nurse is silly, and Mercutio's personality often overshadows the main characters. He is witty, sharp, and comical.

Nurse:

Hie you to church; I must another way,
To fetch a ladder, by the which your love
Must climb a bird's nest soon when it is dark.
I am the drudge, and toil in your delight;
But you shall bear the burden soon at night.

Mercutio even goes so far as to joke while lying at death's door.

No, ’tis not so deep as a well nor so wide as a church-door, but ’tis enough, ’twill serve. Ask for me tomorrow, and you shall find me a grave man. I am peppered, I warrant, for this world. A plague o' both your houses! Zounds, a dog, a rat, a mouse, a cat to scratch a man to death! A braggart, a rogue, a villain that fights by the book of arithmetic! Why the devil came you between us? I was hurt under your arm.