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LaVar Ball has heard the trade rumors involving Lonzo Ball going to the Spurs ... and has a message for the Lakers:

"If they wanna trade him, trade him. It'll be the worst move they ever made."

LaVar went off at his JBA season opener on Thursday afternoon -- when we asked about the rumblings that Magic Johnson could ship Lonzo to San Antonio to get Kawhi Leonard.

"If they wanna trade him, trade him. If they don't wanna trade him, keep him. He's gonna do his thing. I'm not worried about no trades.

LaVar says he's still 100% confident all 3 of his boys will eventually play on the same NBA team, despite the fact LiAngelo wasn't drafted on Thursday.

"He'll come in the back door as a free agent," LaVar explained.