My guy self is completely fake, dorky, insecure, and unattractive. He's also a good shield, unfortunately.
Sometimes, when I'm feeling really self-conscious, I almost seem to rely on the guy side as a suit of armor, or maybe more like a human punching bag. My thought process is something like, "If (whoever I have paranoid feelings about being judged by, despite them being polite) is busy looking down on guy me, they can't do anything to hurt the actual me."
This even happens around people that know I'm trans. Sometimes, I feel like if I stay in guy mode, they'll assume I have a woman mode that's really awesome and feminine. But that if I go into woman mode in front of them, they'll think I'm "fake" because I'm not ready yet. (In actuality, most people like my woman mode much better, but it took me a long time to realize that and old habits die hard.)