"You look pissed"

Well I don't know about any of you but I have to say it's a great day when your bosses boss pulls you into there office to tell you that your body language is poor, your face scrunches up and basically you look pissed during staff meetings. I have to say it is a very odd conversation to have. First you wonder what they are talking about then you wonder how long have they been starring at you and then you think "Give me a break!", you don't have better things to do then check out my body language. So I watch my bosses boss do an interpretation at her chair and I am thinking to myself - this isn't real and they wish they could photograph me for display and proof. Then they proceed to tell me that they have noticed in the pass that it's my domineer and I should really think about how I am portraying myself in a large group setting. My question is "How do you respond?", "What is the appropriate close to this discussion?" I was tossing and turning my thoughts and thank them for the comments and said I would try harder on giving better facial expressions during all meetings. So right after my work day is done I am going to by a traveling mirror and some legalized substance that will keep me wired and super charged.