A psychiatrist is doing rounds in his asylum with a couple of students. They look in on one patient and the psychiatrist says to his students, "Sometimes this fellow thinks he's a temptress in a Bizet opera, but today, as you can see from his goose stepping, he thinks he's the World War II head of the Nazi Luftwaffe. What condition do you think he's suffering from?"
The first student replies, "Is he a paranoid schizophrenic with a multiple personality disorder?"
The second student says, "No, I think he just doesn't know whether he's Carmen or Goering."