This is pretty much what keeps girls from telling that they're girls in games.
Playing TF2 on my regular server, this happens a fair bit.
*Girl joins, and says hello to everyone* (It's obvious that it's a girl due to the voice)
Some moron yells
"HOLY CRAP! It's a GIRL playing Team Fortress 2"
*Girl leaves*
Every bloody time someone realizes there's a girl, someone yells "OMG! - a girl!". Every time.
I have a friend who actually quit playing games for that reason.
Well, anyway. Most girls won't say that they're girls (partially for that reason).
52% of all the people on the world are women. You can't seriously be surprised that there's 1 among the 20 of you.
(This was actually a bit out of context with the thread, I'm not sure why I posted it).
Edit:
Oh, and it's even worse when I come in and say "hello!". "OMG! It's a girl!". I just have a high pitched voice darnit!
http://www.vgchartz.com/games/userreviewdisp.php?id=261
That is VGChartz LONGEST review. And it's NOT Cute Kitten DS