A person or persons involved in the hardcore/metalcore scene that is prone to violence and other illegal activities associated with the term "thug". Not always an in your face kind of person, they tend to keep quite untill confronted with something that upsets them. The end result is usually physical confrontation or verbal abuse from the offended.
"Those thugxcore kids are just too much for me. John made a comment to one of them and he ended up getting his ass kicked. They are pretty quite untill someone says something that upsets them."