After Benedick has been tricked into believing that Beatrice has feelings for him, they meet for dinner. William Shakespeare writes:
Beatrice: Against my will I am sent to bid you come in to dinner.
Benedick: Fair Beatrice, I thank you for your pains.
Beatrice: I took no more pains for those thanks than you take pains to thank me: if it had been painful, I would not have come.
He's expecting a woman with a crush, she's her normal sarcastic self, and the audience is amused at the wordplay between them. Because her response subverts his expectations, it's even funnier.
Beatrice is the center for many of the humorous parts of the play. For example, in an exchange with a messenger, she says:
Messenger: I see, lady, the gentleman is not in your books.
Beatrice: No; and if he were, I would burn my study.
Though she and Benedick have issues between them, she doesn't actually hate him outright. She's dramatic and says things in a way to amuse people....
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