"Sure am, Princess." Ha! Qrow 1, literal teenager 0. He's... crowing over this underhanded victory, but only on the inside, because he suspects that Weiss will actually stab him if he laughs out loud. That would be awfully uncouth for the Schnee heiress, but she could present a reasonable argument that he deserved it.

Qrow does manage to conceal his smirk until she turns around, but it's short lived. Judging by those dainty coughs, it sounds like the poor girl followed his example a little too closely...

"Oh, my bad. Should've warned you not to down it all at once like that."