Matt Barnes, Derek Fisher 'Already Caught These Hands!'

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 ... and the troll had to reference Barnes' infamous incident with the then-Knicks coach.

"This exactly why Derek Fisher be f*cking ya baby momma you slow corny motherf*cker f*ck you for ruining all those Lob City squads with your sh*tty defense," the troll said to Barnes.

Anyone who knows Barnes knows the dude ain't gonna ignore that, so he hit the troll back with "After you done being mad go wash that green off your neck from that fake ass chain B*tch!"

The troll's response is a bit too NSFW to post word-for-word ... so we'll just say he mentioned Fisher and Barnes' ex-wife, Gloria Govan, again ... as well as calling him out for not being in the league anymore.

Barnes' response?? "I retired d*ckhead.. 15yrs & still being paid until November 2020! You gotta do better than DFish jokes. He already caught these hands. You can be nxt "