Beatrice's 'If I were a man' speech, when she shows Benedick and the audience exactly how little she is prepared to take Claudio and Don Pedro's shitty treatment of Hero, and actually convinces Benedick to challenge Claudio to a duel since she can't do it herself, however much she'd love to.
Beatrice: Is he not approved in the height a villain, that hath slandered, scorned, dishonored my kinswoman? Oh, that I were a man! What, bear her in hand until they come to take hands and then, with public accusation, uncovered slander, unmitigated rancor—O God, that I were a man! I would eat his heart in the marketplace.
Benedick: Hear me, Beatrice,—
Beatrice: Talk with a man out at a window! a proper saying!
Benedick: Nay, but Beatrice,—
Beatrice: Sweet Hero! she is wronged, she is slandered, she is undone.
Beatrice: Princes and counties! Surely, a princely testimony, a goodly Count Comfect; a sweet gallant, surely! O! that I were a man for his sake, or that I had any friend would be a man for my sake! But manhood is melted into cursies, valour into compliment, and men are only turned into tongue, and trim ones too: he is now as valiant as Hercules, that only tells a lie and swears it. I cannot be a man with wishing, therefore I will die a woman with grieving.