Who are you?
I don't know!
what are you doing here?
I don't know!

I was looking at you, but I don't know who you are!
I'm still looking at you, but I still don't know who you are!
Do you know who you are?
I don't know!

Is that really who you are?
I don't know!
who could know who you are?
I don't know!