I was recently called out on my agoraphobia in front of a quiet airport waiting room asked to declare why I was being boarded early and what makes me agoraphobic because I "looked normal." Ultimate public humiliation. But refusing the request of airport staff doesn't usually bode well for you.
In a normal situation, aka no one's asking me how I'm mentally ill, I would cover it with normal, boring facts like where I'm from, what university I attended, what I majored in...at 25 there's not much more I can say.
Whatever is relevant to the people listening I suppose.