I have a tendency to lean one way or another or even lean back when I'm taking fire and moving from side to side. I'll also move my head around like I'm actually there looking for stuff. I don't do it on purpose, but I realize I'm doing it sometimes. At least I don't feal the need to talk to the NPCs or read my speech choice out loud like one of my friends does. He gets into games a little too much, I think, but to each their own I guess.