In our firm of about 1000 people, I am working with a group of developers on a minor project. We've been assigned to work with a man who pretends to be a woman. He's making some weird demands, such as getting upset whenever we call him a he (which we obviously do out of habit, I mean, what are we supposed to do, change our instincts over night?) and he also demands to use the ladies toilet, which makes our only female coworker quite uncomfortable. He makes weird noises in the bathroom, she says, and insists on making weird, unnatural chitchat with her about "the boys" (i.e., us...).

How to deal with this situation? We do not want to be discriminatory against an LGBT person, but we also don't want to have to deal with their demands which cause problems for us. Obviously taking this to HR is extremely delicate, as their first impression may very well be that we just don't like LGBT people.