Quote #2
ABRAHAM
Do you bite your thumb at us, sir?
SAMPSON
I do bite my thumb, sir.
ABRAHAM
Do you bite your thumb at us, sir?
SAMPSON
[Aside to GREGORY] Is the law of our side, if I say ay? GREGORY
No.
SAMPSON
No, sir, I do not bite my thumb at you, sir, but I bite my thumb, sir. (1.1.1)

You might be wondering what the heck Sampson's up to when he spots the Montague's servants on the streets and announces "I will bite my thumb at them, which is disgrace to them if they bear it" (1.1.13). Basically, thumb biting, which involves biting and then flicking one's thumb from behind the upper teeth, is a Shakespearean version of flipping someone the bird. Now, Sampson (a Capulet servant) doesn't have a good reason to insult the Montagues' servants – he's basically looking to stir up trouble because his masters are feuding with the Montagues. Plus, Sampson's too much of a coward to own up to his silly gesture because the "law" won't be on his "side" if his thumb biting causes a big old brawl (he doesn't want to get busted for causing a fracas). What's the point of all this? Well, the Capulet/Montague feud, which has obviously trickled down to involve their servants, is completely absurd. Just like Sampson's thumb biting.

Quote #3
PRINCE
What, ho! you men, you beasts,
That quench the fire of your pernicious rage
With purple fountains issuing from your veins,
On pain of torture, from those bloody hands
Throw your mistemper'd weapons to the ground […]
Three civil brawls, bred of an airy word,
By thee, old Capulet, and Montague,
Have thrice disturb'd the quiet of our streets,
And made Verona's ancient citizens
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