Even as a statue, Discord can sense when there is disharmony in Equestria. He also knows that they know he has the power to end it. He's not exactly thrilled about being thought of as a weapon, but he'd put up with it if that's what it would take to get him out of that stone. Besides, he thought being a weapon had a bit more dignity in it than being a decoration.

Fluttershy is feeling a bit down after her critters have gone to sleep for the winter. Discord decides to lighten the mood in his own way. Obvious 40 Year Old Virgin reference.