Trevor Ariza's Grandpa -- I'd 'Kick the S**t' Outta Matt Barnes ... If He Trash Talked Me!

This video is AWESOME!!!

Trevor Ariza's grandfather says if Matt Barnes tried to talk smack to him during a game like he did to James Harden's mother ... "We'd have to kick the s**t out of him!"

Osvaldo Ariza was on his way in to Staples Center last night when we he made it clear ... the Ariza family doesn't mess around.

As far as the situation between Barnes and Harden's mom ... Ariza says he's not worried about Monja Willis because she's a tough chick who can definitely take care of herself.