Steve Kerr went BALLISTIC on a ref during the Warriors' game against the Sacramento Kings on Monday night -- and the whole profanity-laced rant was caught on a hot mic!!!

The blowup all started near the end of the first half ... when Kerr argued a Kings layup shouldn't have counted because there was a foul before the basket.

The GSW head coach received a technical foul for chirpin' the refs ... and then he decided to get his money's worth -- going BANANAS on the zebras.

The transcript? "Wake your ass up! Wake your ass up! Wake up! Wake up! Wake the f**k up!"

Kerr eventually cooled down and was escorted off the floor ... but his speech clearly didn't fire up his squad -- 'cause the Dubs ended up losing 111-98.

Of course, it's been a pretty miserable year for Kerr and the Warriors outside of Thursday's loss ... they've won just 9 games this season without superstars Klay Thompson and Steph Curry.