Grandpa Ball: LaVar Learned Everything From Me!

Here he is ... the man who REALLY created the Big Baller empire -- Grandpa Ball -- and he's spilling some family secrets to TMZ Sports!

LaVar's dad was at LAX after returning from the NBA Draft -- and says LaVar treated the entire Ball family to one of the best meals of their lives after Lonzo Ball got picked #2 by the Lakers.

"I had the best of everything!"

Grandpa says he couldn't be more proud of his son and grandson -- but revealed some interesting differences about his parenting style.

He also revealed his nickname for his son -- and why he doesn't call him "LaVar" like everyone else.