[header] How to deal with a hysterical stranger [title] Figure out why the person in front of us is acting hysterically. [step] This may sound a simple task to do, but bear in mind that the reason why somebody is angry, unreasonable and even aggressive might be much more complicated than what you primarily considered. Try to reason the other by your words if possible to calm the hysteria away. 
Never act aggressively! Things will just get worse, plus you might also hurt yourself or even end being beaten. [title] Be aware that there isn't always a quick answer, or anything you can do.