Actually, I do that quite a bit. It's something I've done since I was a kid, my mom made sure to remind me how much noise I made while playing games. I would constantly annoy her with my sound effects and talking to myself. I'm 23 and I still do it. The funny part is...
I usually only make noises and talk to myself if there are people nearby while I'm playing a game. You'd think that it would be the opposite, but for some reason when I have an audience I'm more inclined to be loud during a game. I cuss a lot more if something irritates me. I don't make as many noises as I did as a kid, mostly it's talking to myself now. If people aren't around me, I'm much more quiet, only rarely throwing out a cuss word if something irritates me.
When I'm playing online and I'm alone at my house, I'm usually pretty quiet too, only talking to team mates slightly, if at all. I usually only talk if I'm playing with friends online.
So yeah, I wish I knew why I make an ass out of myself with people around me to watch, but when nobody is around and I can make an ass out of myself privately, I don't do it.