Oh my gosh, a female! *adjusts tie, slicks back hair*
I carry on with the bloody game! Jesus, how socially inept do you have to be to adjust yourself because you hear a girl? It's not like a supermodel just walked into your room naked whilst you're in a lobby, then maybe you'd react to it.
Man, even insinuating that behaviour suddenly takes a turn upon the introduction of the opposite of sex is completely counter-intuitive to the whole image of gamers being socially backwards. I know there are some creeps who suddenly turn on the "charm" when a girl's present (and I mean 'charm' in the loosest way possible), but those are just creeps in general, not just gamers.
Oh, and the only thing worse than men reacting to a woman entering an online game? The woman who has to constantly reiterate her gender, and how despite this self-professed "disability" she's still doing well. Nice work love, hundreds of years of Suffrage all for you to proclaim your gender as a handicap.