"Yeah? I wouldn't put it past you to be that dumb."

Especially when Winchesters are involved - Gabriel wouldn't have been the first archangel he'd knowingly taken on. But Castiel's right, dancing around personal questions is probably the surest way to get rid of Gabriel, or at least to make him uncomfortable. Hence a somewhat abrupt change of subject.

"Specially if you keep drinking that stuff. Might wanna slow down there, champ."