T.T. snapped at the end of the Cavs-Nets game Monday night ... flipping off some courtside fans after Cleveland sealed the W.

The dudes on the receiving end were pretty shocked ... you can hear them yelling, "Get out of here, you bum" and "someone's gotta get that on video!"

Of course ... it wasn't as bad as K.D. telling a courtside fan to "watch the f**king game and shut the f**k up" -- but Tristan's DEFINITELY still about to get fined for the incident.

Doesn't seem T.T. cares all that much ... guy's on a hell of a double-double run -- and Cleveland finally snapped its losing streak, which had Tristan feeling himself after the game.

"They better put some respect on my name," he said.

FYI ... Durant was popped $25k for yelling at his heckler earlier this season -- and Patrick Beverley is expected to get more than that for throwing a ball at a fan during a game over the weekend.

Seems these guys really do need to take some advice from Michael Richards ...