What is the best way to respond to being fired from your job?

with class don't sass or swear!, and, unless you really think they have you dead to rights on cause, by filing for unemployment

As to future applications it depends what ends up in your file as to the reason for dismissal

if you were only there a short time you might be able to just loose the job off your resume, if you were there a long time try to negotiate a neutral reason, change in management wanted change in work hours/style of worker/bringing in someone with specific skill and did not want to have you working in essentially a demotion position/etc

Find another place to work

Not showing any emotion. Dont give them the satisfaction of getting a rise out of you. To give in to anger is weakness

know that there is a world full of jobs

confidence