I've only recently come out as trans (ftm) and I've been lucky in that most people are being suportive, and most others going along with it even if they don't get it or aren't really supportive... But I do know a few people who just really don't seem able to understand or accept at all.
I was round at a mates yesterday and after the constant misgendering and mentions of how it was wrong because I'm such a 'beautiful/lovely woman' (I think part of the problem is that he finds me attractive and coming from a religious Irish background that's very confusing for him if I'm a guy) had been going on for quite a while my other mate tried to explain that he shouldn't keep saying that, which lead into a rather heated debate about why I'm chosing to transition - not helped by us all being varying stages of drunk.
It was really stressful to try and get the point across that this is something I need to do, and that I don't really give a toss what anyone else thinks because I have to be able to live with myself. Although my more supportive mate said that I did exactly the right thing by just yelling at him until he shut up and listened (because that fits with his idea of how a guy should act). I'm really not good with confrontation, partly because I used to have a lot of issues with losing my temper and getting violent when I did.
Of course after I left and sobered up a bit I came up with all the points and better explanations I should've made, so hopefully I'll remember them in the future... I'm sure I'll be having plenty of similar experiences...