Whenever your in an auditorium, theater, ect. You always look around for the Phantom of the Opera/Erik. You may even start to sing the theme song:

"In sleep he sang to me. In dreams he came. That voice which calls to me. And speaks my name. And do I dream again? For now I find. The Phantom of the Opera is there. Inside my mind."

And one of these two things will happen:

1.) Your friend will come up behind you and say, "Well yeah he's just in your mind! He's not real."

Or...

2.) You'll hear someone sing, "Sing once again with me. Our strange duet. My power over you. Grows stronger yet. And though you turn from me, to glance behind. The Phantom of the Opera is there. Inside your mind."