You can always play mind games with the immature horny toads.
Tell them, "dude! don't be ghey! this is my sisters computer, I'm just trying it out."
Best way to deal with this is to choose a gender neutral nickname or one that suggests a male (i.e. LordKiller, ikillj00ded, BobVila, BeerBurp, etc) since most servers are unregulated.