Rapper ScHoolboy Q's got an ice-cold reality check for Lonzo Ball -- saying the Lakers superstar needs to get the hell out the studio and "STICK TO BASKETBALL."
With Lonzo droppin' more tracks in recent weeks, we had to ask Q if he wanted to get in on the aspiring emcee's career like DJ Mustard and DJ Quik.
His answer -- "HELL NAH! 'Cause I rather see that n***a score some points and get some damn assists."
But Q ain't hatin' ... telling TMZ Sports he just wants Lonzo to be great on the court.
FYI, dude's a huge Lakers fan, but beefs hard with the Dodgers -- straight-up TRASHING the National League champs for chokin' away the World Series.