Robin Thicke -- See, I Told You I'm Being Good!!

Robin Thicke is on a mission to prove he's done playing grab-ass with chicks while touring ... so he hit up a local b-ball court before his concert Saturday night to shoot hoops with a bunch of dudes.
Thicke stopped by a gym in Connecticut and messed around on the court with the Norwich Free Academy's boys basketball team ... and according to reports he was a pretty decent shooter.

As we previously reported ... Robin is trying to show Paula Patton he can be a good husband and change. For her part, we know she told him she wants a divorce, but she hasn't hired a divorce lawyer -- yet -- and she hasn't completely closed the door.