how do people laugh on command, like the subject matter has nothing funny in it but people laugh as they are talking about it and others smile along while im here with my resting b*tch face like "and what about it?"

To answer your first question : just use the muscles around the mouth. Like we do for most of all our facial feedback.

Your second question, it is called humor and that is very personal I think. Some will laugh at stupid jokes, others don't. I guess you are to smart for the jokes in that case :D

Because they are sick, self absorbed, disordered and should be euthanized. I'm sorry, were you looking for a milder response?

@SanjeevMhn
One has to be broken before
in order to regain / learn controled laughter.