Ok, so if someone tells you they're a chicken, are you going to respect that? What if a white person says they're black? Will you respect that? What if a guy living in a box down by the river says he's your mother? Are you going to be stubborn, hateful, and close-minded, or are you going to give your "mother" a hug?
@cjsummers :
I'm probably going to think they're crazy. If on the other hand an extremely large portion of the population starts thinking they're chickens (or whatever), then I might start thinking I'm crazy. That's a pretty extreme example, though, and I think there is a discernible difference.
If it bothers you that much, why not seek out a transgender community where you can ask questions face to face?