Quote 10
MERCUTIO
Why, is not this better now than groaning
for love? now art thou sociable, now art thou
Romeo, now art thou what thou art, by art as well as
by nature. For this driveling love is like a great
natural that runs lolling up and down to hide his
bauble in a hole.
(2.4.90-95)
Translation: being in love makes Romeo seem like a "natural," i.e. someone who's mentally challenged, and runs around trying to hide a toy. Hm. Is Mercutio a little jealous of Juliet? Is he worried that she's going to break up the band, Yoko-style?
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."