David Arquette SCHOOLED a bunch of rehabbers in L.A. this week ... in more ways than one -- showing off his filthy skills on the basketball court ... then teaching them a thing or two about staying sober.
Sources tell TMZ, several inpatients from a place called Chabad Residential Treatment Center hit up Pan Pacific Park Tuesday for a pick-up basketball game -- but when they arrived, they realized they were short one player.
According to sources, Arquette was standing nearby at the time and noticed they needed a fill-in -- so he offered up his services.
Needless to say, Arquette -- who's famously nasty on the court -- mopped up with his team, who then informed him they were from the local rehab center.
Arquette was moved ... and according to sources, the actor -- who's celebrating 14 months sober himself -- gave them some sage advice about staying clean. It was pretty awesome.