As we reported, Twist has been accused of battering some girl at Bieber's Calabasas mansion Thursday morning -- but it's only the latest example of Twist's reckless behavior ... a list that includes smoking pot, driving like a lunatic, and getting a DUI.
Bieber has refused to turn his back on Twist once already -- but Scooter has had enough, telling Bieber the battery allegations are the last straw.
We're told Scooter is putting his foot down, insisting Twist is nothing but a parasite sucking Bieber dry -- and the singer needs to drop him like a hot potato stat ... before he does any more damage.
But stupidly, Bieber is still sticking by his buddy -- in fact, we're told he and Scooter had a blowout fight on Thursday when Scooter said Twist had to go.
Which means Twist's days are numbered -- because in a fight between Scooter and Twist, Bieber will almost certainly side with his trusted manager. He'd be dumb not to. Then again, dumb has kinda been Bieber's M.O. recently.