[Fey]

I've multiple friends that get mistaken for the opposite gender. Most are female that get mistaken male, but a couple male that get taken for women. Usually they're okay with the mistakes, though there's been a few rather hilarious(to me) mistakes when they would go to use public restrooms. One resulting in a girly scream of 'I'm a woman!!'

And I'll admit, in a couple of cases I didn't even think to GUESS that they were the other gender. I have a good friend that until I met her for the fourth time did I realize she was in fact female. But since she gets mildly perturbed when people INSIST she's a guy I don't often tell her when someone around makes the mistake.

As to crossdressing, I've done it a few times for costumes, but I really don't fool anyone as I'm well proportioned as a woman. No amount of compression can take it away.