Hamlet, the Prince of Denmark, son to Queen Gertrude and to the late King Hamlet, and nephew/step-son to the new King Claudius. Hamlet is depressed, bitter and full of hate for his uncle and disgusted at his mother for marrying his uncle so quickly after his father died. And in the play he uses his "madness" to confuse, scare and to express some of his true feelings.
In Act II, scene ii, Polonius attempts to strike up a conversation with Hamlet, who appears insane; insults Polonius without him ever really realizing. He calls Polonius a "fishmonger" (II.ii.174), like he didn't recognize him and then a couple seconds later Hamlet asks "Have you a daughter" (II.ii.182), thus confusing Polonius, because two seconds ago Hamlet didn't know who Polonius was. Polonius comments that while Hamlet is clearly mad, his replies are sometimes "pregnant" with meaning (II.ii.206).
In Act III, scene ii, Hamlet asks Polonius if he sees the "cloud that's almost in shape of a camel?" (III.ii.370-371)
and he replies that it does looks "like a camel" (III.ii.372). Next Hamlet says that it looks more "like a weasel" (III.ii.373) and stupidly Polonius replies that "it is back'd like a weasel" (III.ii.374). Hamlet is deliberately playing the fool with Polonius, just to make him look stupid. But Polonius is too scared to say anything back because he probably believes it is dangerous to cross a madman.
Many of Hamlet's seemingly insane statements have truth and are a way for Hamlet to express some of his true feelings. Hamlet doesn't like Polonius and he uses his madness to insult him without Polonius realizing that he's doing it; he figures it's just the insanity talking. He makes fun of Polonius's appearance, he says "old men have grey beards", "their faces are...