Staying calm and speaking during confrontations is a learnable skill. I humbly recommend reading the book Crucial Conversations, if you haven't read it, then practicing the techniques.
I tell my "underlings" to breathe (with their diaphragm), to take their time, and to carry their voice.
Good book recommendation but my personal reaction if I ever encountered this during an interview would simply be standing up and excusing myself due to the lack of "cultural fit". Sure sometimes you need a job but compromising during job interviews is a pretty bad thing imo. You'll spend a good chunk of your time at a place, just walk if it smells funny.
Yeah, but another valuable skill is knowing that if you are treated this badly in an interview that even if you really want the job, sometimes it's best to walk away.
I would probably politely ask the person if they were acting like a clown as an interview technique or if they were in fact an clown. No need to bother with disrespectful people.
I tell my "underlings" to breathe (with their diaphragm), to take their time, and to carry their voice.
[1] http://www.amazon.com/Crucial-Conversations-Talking-Stakes-S...