Juliet expresses her fear of waking up in the tomb when she says, "How if, when I am laid into the tomb, I wake before the time that Romeo come to redeem me?" (IV.iii. 31-32)
Where is ROMEO?!
Juliet expresses her fear of going insane when she says, "So early waking, what with loathsome smells, And shrieks like mandrakes' torn out of the earth, That living mortals, hearing them, run mad" (IV.iii. 31-32)
What are those sounds?! Am I going mad?
Juliette thinks she will go crazy and "play with here forefathers joints." (IV.iii.51)
Juliet thinks that "with a club, dash out my desperate bones." (IV.iii.54)