Justin Bieber's Ferrari Cop Blocked Again

Justin Bieber oughta think twice before loaning his car out ... because it was involved in yet another run-in with cops.

Bieber wasn't driving. The guy behind the wheel -- Lil Za -- was pulled over in West Hollywood -- apparently for tinted windows -- today at around 1:30 AM. The driver didn't have a license, so deputies put him in the back of the squad car and it looked like he was under arrest. Driving without having a license is an arrestable offense.

But deputies cut the dude a break, and he was cited and released.

You'll recall, a month ago to the day ... another one of Bieber's friends -- Lil Twist -- took Bieber's car for a high-speed ride, was pulled over by cops and a photog was struck and killed by another car while shooting the traffic stop.

As for the latest incident ... Bieber's friend flipped photogs off while sitting in the back of the cop car.