hardcore kids are douche bags between the ages of 15 and 20, I've seen one in their 30's though, so I guess some kids never grow out of their faggotry.
they take themselves way too seriously and all start terrible bands with "br00tal" names.
they say things such as "wicked" "siqq" and "fukkin brootal SON!"
they also get TERRIBLE tattoos, generally they turn into TERRIBLE sleeves, and they then brag to their friends about how "siqq" their tattoos are.
hardcore kids are fond of getting ridiculous piercings including:
lip web piercings
ridiculously large gauges
double nose rings
the cooler ones will grow beards, but seeing as most hardcore kids are prepubescent teens with nothing better to do with their time, they'll have ugly scruff.
hardcore kids are also fond of being "straight-edge" and "vegans"
they think this makes them more br00tal, but as you know there's nothing more brutal than killing your liver and lungs with drinking and smoking. Killing animals is also pretty brutal.
this is a made-up term by a pseudo-scene where white kids put up the "demon claw" and jump around with no beat or time signature. They like to punch the air and do windmills, generally they'll wind up with a headache and then punch you for smoking a cigarette.
Overall, hardcore kids listen to terrible bands that all sound the same, take themselves way too seriously, and will ultimately get nowhere in life with their large gauges and piercing scars.
Guy: "Dude did you see those hardcore kids!?"
Me: "Yeah what a bunch of queers"