Matt Barnes is FED UP with the Derek Fisher jokes ... going scorched earth on an internet troll for heckling him about his old enemy, saying, "He already caught these hands. You can be nxt."
Here's the backstory -- Barnes went to Twitter on Thursday to talk about the Warriors and Clippers game, saying "Hopefully y’all will stop w this PatBev locking up or shutting down KD.. Only person that can stop KD is Westbrook."
Harmless tweet, right? Except, of course, someone had to disagree. After all, this *is* the internet we're talking about .