Hamlet Act I, Scene iii Summary

Laertes, a young lord about to depart for Paris, has some dear parting words with his sister, Ophelia.
He asks her about her budding relationship with Prince Hamlet, and details that because Hamlet is above her (in the social status way), he might have to marry someone else for the sake of the state. Also, he's worried that Hamlet might take advantage of her. He warns her that if she has sex with Hamlet, she'll be damaged goods.
Ophelia, it turns out, is no wimp because she tells Laertes not to be a hypocrite. In other words, he's probably been sleeping around pre-maritally himself.
Polonius, father of Laertes and Ophelia, enters and gives his son a lot of long-winded advice. He tells the young man to listen more than he talks; to not borrow or lend money; to not wear gold and silver at the same time (he actually says not to be gaudy); and in a line of great meter and measure: "This above all, to thine own self be true."
When Laertes finally leaves, Polonius tells his daughter that Hamlet only wants to sleep with her. He also tells Ophelia she's an idiot if she actually believes Hamlet loves her. He orders her to stop seeing him and uses the word "pooh" in the process. She agrees.