Justin Bieber stopped traffic - LITERALLY - Friday afternoon in Beverly Hills as he had his driver stop in the middle of the street so he could ditch the car and do some grinding at City Hall!

The Biebster stepped out of his black SUV, carefully exchanged his Yeezy Boosts for some old-school black-and-white checkerboard slip-on Vans and headed over to some tempting steps on city property -- right next door to the police department. Risky!

After showing off and landing a few tricks, Biebs high-fived some photographers and got back in his waiting car. He gave us a quick comment on Lamar Odom before speeding away ...