"Hardcore dancing" is easily defined as a way for those girl pants-wearing, emo haircut sporting, brainless trend following yuppie kids to act tough. Hardcore dancing often looks as if the people performing the dance are going to mosh, but they actually dont, and when one does get hit by another, they often retreat out of the little circle-jerk they call the "pit" and go cry to their emo girlfriends. Hardcore dancing should only be attempted by the extremely homosexual.
"Dude, i was totally kicking that invisible ninja's ass, until some idiot completely like clipped me with his plaid converse. Kicking other people in the pit is so totally not hardcore dancing"