Act 2, Scene 2:
HAMLET: My excellent good friends! How dost thou,
Guildenstern? Ah, Rosencrantz! Good lads, how do ye both?
ROSENCRANTZ: As the indifferent children of the earth.
GUILDENSTERN: Happy, in that we are not over-happy;
On fortune's cap we are not the very button.
HAMLET: Nor the soles of her shoe?
ROSENCRANTZ: Neither, my lord.
HAMLET: Then you live about her waist, or in the middle of
her favours?
GUILDENSTERN: 'Faith, her privates we.
HAMLET: In the secret parts of fortune? O, most true; she
is a strumpet.
As an explanatory note to tiefling's writeup, "nothing" was slang in Shakespeare's time for vagina. This will help you to appreciate the joke in the exchange between Hamlet and Ophelia, and indeed to get a full sense of how deeply smutty some of Shakespeare's wordplay can be.