LANE: All three of them huh?
RORY: Double, double toil and trouble.
LANE: Well, it should make for an interesting afternoon.
RORY: With the pricking of my thumb, something wicked this way comes.
LANE: You’re doing very well in the Shakespeare class aren’t you?
Rory is quoting from the tragedy Macbeth by William Shakespeare, first staged in 1606. In the play, Macbeth meets three witches whose prophecies drive him to murder, and eventually lead to his own demise.
Rory quotes lines from the three witches, linking Paris, Louise, and Madeline with the grim trio, and also with the “something wicked” that is coming. Lane’s comment suggests that Rory studied the play in her English Literature class.