I do it off and on. Sometimes I get on a kick for a bit. Then other times not so much.
As someone who has done acting (in a professional haunted house), is where I did it the most. My favorite is during halloween, my favorite character is a clown I have developed over the years who has a questionable gender. Among some offensive attitudes. Often I will be looking like a cute clown girl, and then respond to people in a very deep voice.. bwhahaha.. October is my favorite month to screw with gender assumptions. (In either direction). I am naturally fairly androgynous looking, passing is more a matter of giving off more gender cues for one or the other.
I live in a very low population density area. Everyone who lives here (small town stuff) Im pretty sure is completely confused by me, since they deal with me on a day to day basis. They also see me with both genders over the years. A few people are brave enough to ask me directly. Most people try and ask people who are close to me when im not around. My friends always say "Why dont you ask her, she will tell you in full detail". Unless Im feeling extra snarky... then I might say "Only one way to find out", and give a wink.