Guy A: I'm going to flirt with that girl.
Guy B: You know she's going out with the captain of the football team, right?
Guy A: Yup.
Guy B: You're dancing with the devil's wife.
First of all, "hxc" is a lazy way of saying Hardcore, which usually means the genre of music that has a mix of singing and screaming (the better hardcore bands are closer to metal, the bands that are hxc danced to are "scene")
Hardcore dancing is basically a scenekid's equivalent to a mosh pit. It is when someone with a thousand different colors in their hair flail their arms and legs around like a moron, but won't go into the pit and shove people around.
A girl with straightened hair, dyed all the colors of the goddamn rainbow, ran into the open center of the crowd and began hxc dancing - and was promptly knocked unconcious by a metalhead who ran into her from the most pit
"That girl is HOT!" - Guy #1
"Dude." - Guy #2
"What?" - Guy #1
"She is a Dancing Nancy." - Guy #2
"A what?" - Guy #1
"A transvestite prostitute." - Guy #2
"Dude. Eww." - Guy #1
"I dunno... I'd still tap that." - Guy #2
"Dude. No." - Guy #1
Acrobatic, kung-fu style dancing to hardcore music such as Blood for Blood, Earth Crisis and 25 ta Life, but has leaked into metallic hardcore, nu-metal/metal and emo scenes over time. Generally reserved for macho dudes, dudes trying to get into a fight, or dudes trying to impress other dudes with their "skills". Types of hardcore dancing includes spin kicks, "picking up change", pile-ons, as well as other physically challenging (and often hilarious to watch) martial-arts style moves. Can be enjoyed by straightedge and non-straightedge dudes alike, yet girls seem to shy away from displaying such behaviors too often.
"Dude, we totally wall-of-death'ed those meathead fucks who were hardcore dancing at that Municipal Waste show."