In the when things go wrong category:
Acts 19: 13-17
...some of the itinerant Jewish exorcisms undertook to pronounce the name of the Lord Jesus over those who had evil spirits, saying, "I adjure you by the Jesus whom Paul preaches." Seven sons of a Jewish high priest named Sceva were doing this. But the evil spirit answered them, "Jesus I know, and Paul I know; but who are you?" And the man in whom the evil spirit was leaped on them, mastered all of them, so that they fled out of that house naked and wounded. (My bold emphasis!)
Needless to say the demon's "who are you?" response delights me.