SAMPSON, aside to Gregory Is the law of our side, if I say 'Ay'?
GREGORY, aside to Sampson
No. SAMPSON No, sir, I do not bite my thumb at you, sir, but I bite my thumb, sir. (1.1.45-52)
This is about the stupidest reason to start a street brawl ever. (Is there ever a good reason to start a street brawl?)
Act 1, Scene 4
MERCUTIO O, then I see Queen Mab hath been with you. She is the fairies' midwife, and she comes In shape no bigger than an agate stone On the fore-finger of an alderman, […] This is the hag, when maids lie on their backs, That presses them and learns them first to bear, Making them women of good carriage. This is she—
ROMEO Peace, peace, Mercutio, peace. Thou talk'st of nothing.
MERCUTIO True, I talk of dreams, Which are the children of an idle brain, (1.4.58-61; 97-104)
Fed up with Romeo's lovesick moping for Rosaline and his claim that he had a steamy "dream" the night before, Mercutio taunts his buddy by saying that Queen Mab must have paid him a visit. (Queen Mab is a tiny fairy that brings dreams to lovers like Romeo and you can read more about her in "Symbols.") Mercutio also informs Romeo that dreams "are the children of an idle brain," which is another way of saying that Romeo is an idiot and his dreams about Rosaline are ridiculous (1.4). Given the context of the speech, it seems like Mercutio is suggesting that, like Queen Mab, dreams (especially Romeo's) are small and insignificant.
But Mercutio isn't the only one to point out when his pal is behaving foolishly. Romeo criticizes Mercutio's crazy rant when he yells "Peace, peace, Mercutio, peace! Thou talk'st of nothing."
Act 1, Scene 5
TYBALT This, by his voice, should be a Montague.—
Fetch me my rapier, boy. What dares the slave Come hither, covered with an antic face To fleer and scorn at our solemnity? Now, by the stock and honor of my kin, To strike him dead I hold it not a sin. (1.5.61-67)
Tybalt's all miffed that Romeo comes in to "scorn at our solemnity," i.e. he's shown up to the Capulet ball. But, um, a masked ball isn't exactly a solemn occasion, is it?
Act 2, Scene 3
FRIAR LAURENCE Holy Saint Francis, what a change is here! Is Rosaline, whom thou didst love so dear, So soon forsaken? Young men's love then lies Not truly in their hearts, but in their eyes. Jesu Maria, what a deal of brine Hath washed thy sallow cheeks for Rosaline! How much salt water thrown away in waste To season love, that of it doth not taste! The sun not yet thy sighs from heaven clears, Thy old groans ring yet in my ancient ears. Lo, here upon thy cheek the stain doth sit Of an old tear that is not washed off yet. (2.3.69-80)
When Romeo bursts into Friar Laurence's chamber and declares his love for Juliet, the Friar points out that Romeo was all hot for Rosaline just the other day and now he says he's into Juliet. Good point. Yet, this same Friar agrees to help Romeo and Juliet get hitched just a few lines later. What's up with that?
ROMEO O, let us hence. I stand on sudden haste.
FRIAR LAURENCE Wisely and slow. They stumble that run fast. (2.3.100-101)
When Romeo wants to rush off to marry Juliet, the Friar warns him to slow down emotionally, as well as physically. But the Friar isn't exactly being all calm and level-headed, is he?
Act 2, Scene 6
FRIAR LAURENCE These violent delights have violent ends And in their triumph die, like fire and powder, Which as they kiss consume. The sweetest honey Is loathsome in his own deliciousness And in the taste confounds the appetite. Therefore love moderately. Long love doth so. Too swift arrives as tardy as too slow. (2.6.9-15)
The Friar tries (and fails) to convince Romeo to love more calmly. The Friar would sound like the play's voice of reason, except that he behaves more foolishly than anyone. And the most foolish guy, Mercutio? He's the only one who really seems to get it: the feud is dumb, and Romeo is an idiot. No wonder Shakespeare kills him off.
Act 3, Scene 3
FRIAR LAURENCE Hold thy desperate hand! Art thou a man? Thy form cries out thou art. Thy tears are womanish; thy wild acts denote The unreasonable fury of a beast. Unseemly woman in a seeming man, Or ill-beseeming beast in seeming both! Thou hast amazed me. By my holy order, I thought thy disposition better tempered. Hast thou slain Tybalt? wilt thou slay thyself, And slay thy lady that in thy life lives, By doing damnèd hate upon thyself? (3.3.118-128)
Here, Friar Laurence and Juliet's Nurse prevent Romeo from committing suicide (because he's afraid Juliet hates him for killing her cousin, Tybalt). The Friar's critique of Romeo's rash and foolish behavior is successful (here anyway), but we're not sure which is more foolish—Romeo's desire to stab himself with his sword or Friar Laurence's insinuation that Romeo's emotions are "womanish" and unmanly.
Act 3, Scene 4
CAPULET Monday, ha ha! Well, Wednesday is too soon. O' Thursday let it be.—O' Thursday, tell her, She shall be married to this noble earl.—
Will you be ready? Do you like this haste? […]
PARIS My lord, I would that Thursday were tomorrow. (3.4.22-25; 32)
It's not just the young who rush into things; Juliet's father makes hasty decisions, too. Here, he argues that Juliet and Paris can't be married fast enough. What happened to waiting until she finishes puberty? (Oh, quick brain snack: puberty on average happened later for people in the 16th century—and most centuries, up until the middle of the twentieth. Good nutrition and possibly other factors have lowered the age a lot.)
Act 4, Scene 1
FRIAR LAURENCE On Thursday, sir? The time is very short.
PARIS My father Capulet will have it so, And I am nothing slow to slack his haste. (4.1.1-3)
Supposedly wiser and calmer than Romeo and Juliet, Lord Capulet and Paris also make a hasty decision that results in tragedy. Guess the adults don't have an advantage here.
Act 5, Scene 3
FRIAR LAURENCE Saint Francis be my speed! How oft tonight Have my old feet stumbled at graves! (5.3.121-122)
Friar Laurence doesn't move fast enough to save Romeo and Juliet. Still, despite his slowness, he stumbles (literally and symbolically) as much as those who move more quickly.