Justin Bieber's Posse -- TERRORIZING CALABASAS ... CAUGHT ON TAPE!

Justin Bieber's housemates -- Lil Za & Lil Twist -- are law-breaking, aggressive punks ... who dangerously rocketed through the streets of Calabasas and cussed out their neighbor ... and TMZ has the footage.

The latest incident went down Thursday inside Bieber's exclusive gated community -- The Oaks -- where one of Bieber's neighbors witnessed Za and Twist tearing up the streets in JB's cars ... a black Range Rover and the infamous white Ferrari.

You'll see a lady with a camera driving 25mph -- the speed limit -- as the two cars are stopped in front of her ... one in the oncoming traffic lane.

As the woman passes Bieber's cars ... Za and Twist turn on the jets and screech past her at speeds way in excess of the limit.

It all comes to a head at one of the gates in the community, where Za gets out of his car, aggressively confronts the woman -- and proclaims he's a resident of The Oaks with this glib gem ... "I live with Justin Bieber and you know I do."

He then tells the woman, "F**k you. Get the f**k out of here."