What are some quotes that prove that Hamlet is pretending to be insane?

In  Act II of Shakespeare's "Hamlet," Hamlet bandies words with Polonius, whom he suspects of treachery.  He first calls Polonius "a fishmonger," then he remarks, "Then I would you were so honest a man.  This bandying with words continues as he talks to Guildenstern and Rosencrantz, whom he also suspects.  When Hamlet says, "Denamrk's a prison" (II,ii, 236), the former friends of Hamlet disagree.  To this Hamlet replies,

Why then 'tis none to you; for there is nothing either good or bad, but thinking makes it so.  To me it is a prison.

While these remarks are not insane, they become a cause for some concern by others, especially when they learn that Ophelia has been frightened by him. She tells her father,

My lord, as I was sewing in my closet,/Lord Hamlet with his doublet all unbraced,/No hat upon his head, his stockings fouled,/Ungartered and down-gyved to his ankle,/Pale as his shirt, his knees knocking each other,/And with a look so piteous in purport /As if he had been loosed out of hell/To speak of horrors--he comes before me. (II,i,76-83)

Her father asks if Hamlet is mad for her love.  Ophelia replies that she does not know; she only knows that she fears this affection, telling Polonius,

He took me by the wrist, and held me hard,/Then goes he to the length of all him arm,/And with his other hand thus o'er his brow,/He falls to such perusal of my face/As'a would draw it.  Long stayed he so./At last, a little shaking ofmine arm,/And thrice his head thus waving up and down,/He raised a sigh so piteous and profound /As it did seem to shatter all his bulk...And with his head over his shoulder turned/He seemed to find his way without his eyes...(II,I,88-97)

Later, in Act III, Polonius and Claudiius decide to put Hamlet and Ophelia together to decide if love is what makes Hamlet mad.   When Ophelia greets Hamlet and tries to return his gifts, Hamlet denies having given her anything, subjecting her to paradoxical outbursts (lines 11-114 "Ay, truly....) and criticisms:

Get thee to a nunnery.  Why wouldst thou be a breeder of sinners?  I am myself indifferent honest, but yet I could accuse me of such things that it were better my mother had not borne me. (III,i,119-121).

His remarks about his own mother suggest that Hamlet is still reacting to the realization that his mother has married the murderer of his own father.  His disgust with his mother has engenered misogyny in Hamlet.