I would if I could, but I can't help it.
My default facial expression has always been read as inappropriate for a girl (I guess I look like I'm sad or angry or something) and my emotional reactions also used to get read as inappropriate, so I trained myself to smile in response to basically everything. Angry, upset, frustrated, nervous, shy, it didn't matter, I started converting all of my facial expressions into cheesy grins. And now it's a habit. I'm trying to kill it, but I've had no luck so far.