What is your "writing face"?

I realized tonight that there's something I always do when I'm writing, be it a happy scene, a sad scene, or even a fight scene:  I write with a dopey smile on my face.

Here's a web cam pic of me from five minutes ago.  My face has been like this all night, for so long that my cheeks actually hurt a bit, but I can't stop doing it.  Even now, I'm smiling, and it certainly doesn't have to do with what I'm also watching on TV, because episodes of The Walking Dead - while engrossing - aren't the kind of thing that bring a smile to my face.

That's kind of dark.

Here it is a little lighter.

Why are my cheeks so tired?  Because I'm writing, as in creating new stuff.  I've written three new scenes in my book.   I don't know what it is, but the process of creating just makes me happy, regardless of the actual tone of the scene.  I smile when I'm editing, too, but not nearly as much.  (Oddly enough, I frown when I'm designing covers, but that's because it takes a bit of concentration to get things just right.)

So, I wanna know - what's your writing face?  Do you smile?  Bite your lips?  Narrow your eyes?

Oh, and just out of curiosity, but do any of you find yourself kind of acting things out when you're writing?  Or saying a line out loud with the facial expression your character would be using, just to see if it clicks?  Or am I the only weirdo who does that?