Quote analysis

"You are a saucy boy."
Funny quote which wouldn't really be funny or insulting today, but more creepy, but it would be back then.  I just chose this because I liked it
"But, soft! What light through yonder window breaks? It is the east, and Juliet is the sun!"
Romeo is comparing Juliet to the sun instead of the moon and how he wants her to rise, also similar to the way he says she makes the torches burn bright.  This quote is especially showing how in love he is with Juliet
"A plague o' both your houses!"
Mercutio has been stabbed and is going to die.  He blames the two houses and is angry because it is their feud that ended up getting him killed.  If the houses had stopped fighting all the deaths wouldn't have happened.