Read the full text of Love's Labour's Lost Act 4 Scene 1 with a side-by-side translation HERE.
The girls are on a hunt. The Princess is in a good mood and teases the Forester for not calling her fair (as in beautiful). She plans to kill a deer to win praise.
Costard enters with a letter for Rosaline. Well, it's the wrong letter—the Princess holds Armado's letter to Jaquenetta—but Boyet reads it for laughs, anyway. It's long and ridiculous in its mock-learning. After a good bit of amusement, the Princess informs Costard that he's made a mistake and exits.
Boyet is amused that Berowne's sent Rosaline a letter and teases her about her suitor. She gives it right back to him. She exits and Maria gets in on the game, as does Costard. Lots of fun sexual innuendo ensues about "marks," "pricks," and "upshots."
Left alone, Costard gives a summary of the amusing characters populating the court at the moment.