OLIVER
Where will the old Duke live?
CHARLES
They say he is already in the Forest of Arden,
and a many merry men with him; and there they
live like the old Robin Hood of England. (1.1.112-115)
Because Duke Senior lives in exile with his crew, he's associated with the legendary outlaw Robin Hood, who stole from the rich and gave to the poor, flipping the bird to those in power every chance he got. The play's Forest of Arden, then, becomes associated with England's Sherwood Forest (Robin Hood's neighborhood) and opposition to corrupt authority figures.
Quote 2
OLIVER
Be of good cheer,
youth. You a man? You lack a man's heart.
ROSALIND [as Ganymede]
I do so, I confess it. Ah,
sirrah, a body would think this was well-counterfeited.
I pray you tell your brother how well I
counterfeited. Heigh-ho!
OLIVER [helping Rosalind to rise]
This was not counterfeit; there is too great
testimony in your complexion that it was a passion
of earnest.
ROSALIND [as Ganymede]
Counterfeit, I assure you.
OLIVER
Well then, take a good heart and counterfeit to
be a man.
ROSALIND [as Ganymede]
So I do; but, i' faith, I should
have been a woman by right. (4.3.12)
When Rosalind faints at the sight of Orlando's blood on a handkerchief, she seems to fit the role of the stereotypical woman. This prompts Oliver to order "Ganymede" to buck up and act like a man.
Quote 3
OLIVER
O that your Highness knew my heart in this:
I never loved my brother in my life.
FREDERICK
More villain thou. (3.1.13-15)
You know things are bad when even Duke Frederick thinks you are a villain. We should also point out that Duke Frederick is being a total hypocrite here. After all, he snagged his own brother's title and then booted him and Rosalind out of his dukedom.