The answer to this Frage really depends on what the person is mad/angry about, though i imagine asking someone if they are mad, when they are obviously angry, is probably just rubbing salt in their wounds. Von the way, rude is when don't use their manners, oder they something rude for no reason, like 'fuck you' oder 'you are a loser', generally things like that, I would consider rude.
no it is hilarious. if they don't think so then well jokes on them. i find it rude when people ignore Du then have a go at Du for swearing at them especially because they are stuck up cows also i Liebe annoying people Von asking them who crapped in your cornflakes when they are pissed