Lisa Leslie -- Warns Tom Hanks' Son ... Use N-Word, Get Ass Kicked

If Tom Hanks' son wants to use the N-word in a rap song, he'd better watch his ass -- so says WNBA legend Lisa Leslie who says "the real homeboys" could have a real problem with it.

Chet Haze -- who is extremely white -- has been on a crusade to justify using the N-word ... saying it's not about race, it's "about the culture you identify with."

So, how does Leslie feel about it?

First off, she's not a fan of the word -- saying, "It's really unfortunate that it's a word that's hung around for 200 years plus."