Can I scream at trans people's legal names in a crowd?
Why are you going to scream their legal name like that? It doesn't sound nice.
I didn't know a lot of trans people, and I didn't want my trans friend to have a bad name when out in public.
It's rude to embarrass people like that, trans or otherwise. You shouldn't do that.
It's okay, my friend is okay with it.
Still, you have to be sensitive to the situation and to the trans community. It's not fair for them to be made fun of because they are just like you and me. Maybe you should consider not doing this because it really doesn't mean it's right, even if your friends don't care.