Schizophrenic or Bluetooth Headset?
This is a pretty easy one. You basically decide if a person is talking to themselves... or a person on a bluetooth headset. Granted, even if you SEE a bluetooth headset in their ear, that's not always an indication that they are NOT suffering from multiple personalities.
Essentially, you and your date will keep score while trying to determine if a person is hearing voices in their head, or hearing voices from the bluetooth headset they may be wearing.