Popping shit is a term that means to talk shit about another person or start a fight with them. This term first came around in 1995 era hip hop,
way before the notion of "scene kids" was even
dreamt of.
Since "Popping shit" originated with mid 90s
hiphop, it's perfectly acceptable to say it in public and even makes the person using the term seem more well-read than the average bear.