Doesn't matter if a heckler hurled the n-word, pro athletes like Leonard Fournette need to WALK AWAY from trash talkers ... 'cause if they actually fight, a pro could literally KILL a loudmouthed normie.
That's the advice coming from Charles Barkley -- who's dealt with plenty of hecklers during and after his NBA career.
Chuck knows trash talk is all fun and games until things turn physical -- and that's when things can get way too real.
"If you hit a fan and hurt them, you might KILL them," Barkley explained ... "But the main thing, you just gotta walk away or they're just gonna sue ya."
"Listen, they would never say that to you and fight you in the streets, but if you hit them you're gonna lose a lot of money," Barkley added on his way out of Matsuhisa in L.A.
It's not just Fournette who's been heckled lately, huge NBA stars have been targeted too -- including Kevin Durant, Patrick Beverley and Montrezl Harrell.
"You gotta let it go," Barkley says ... "You got nothing to gain. Suck it up, brother."