How would you react....?

Say "make me."

The very phrase "shut up" is rude in itself. I would be offended though I would consider the source. Some poeple were never taught manners in the first place. I would also consider the context, before I got too nettled. If we're just playing around and I'm picking at a friend then I would laugh and stop picking. But if someone says shut up because they want me to be quiet, then I would be quiet for a while, and then later explain to them that what they said was rude and I did take offense. Often times this won't matter to them but at least I spoke my peice and didn't hold it in so as to just be further irritated.

I would ask that person why I need to shut up

I'd be shocked and actually shut up. I'd make sure though that I never talk again to the person who told me to shut up.

I would say " excuse me??" and unless they gave a heck of a good answer, I would still keep right on talking.

it depends on the situation really. Like if your in class, and your teacher tells you to shut up, you would obviously listen to her, but if it was some random person off the street telling you to shut up, I get angry. I might not do anything physical, but yeah I do get angry.

depends if its a teacher you know you got to keep quiet but like if its some stupid person like a "friend" or some random person you tell them to go somewhere and out of your face

AbrahamLincon was not so good at table manners, while his wife was a perfectionist.
One evening when friends had come and tea was served, Lincon , in a hurry, put his fingers in the sugar bwl and lifted the sugar.
Mrs.. Lincon got furious and splashed the hot water in the kettle on his face! All around were awe struck and looked at that face. He was benignly smiling and had the grace which kept all looking at him for long.
That s why Shakespeare has said : "Patient merit slights of the unworthy take!"
Hpoe you got the answer to your question.

Well you would have to stop and think for a while as to why they're telling you to shut up. And if you deserve it, then shut up! Sorry...

Tell them to shut up and quit telling me to shut up! That's right, I went there!! Lol

Hopefully I would have the presence of mind to keep my mouth shut long enough to consider why they told me that before responding