I was standing in Mor Dhona the other day and someone was shouting in the shoutbox "Megan Lastname is hot! Message her!"
I just thought, wow. That's it right there. Getting "outed" as a girl is the worse than Titan plumes. Except for Hellion, most people assume I'm a dude and I don't often correct them because this behavior is too common.
It's pretty easy to hide in Final Fantasy though. Guys play girl characters with guy names, everyone is a cat or a lala so gender is pretty much completely ambiguous unless you know the person.
Or, unless you're Megan in Mor Dhona who was probably just minding her own fucking business.