Ice Cube & Son -- Boyz-n-the-Brood ... All Love, No Trash Talk

Ice Cube casting his son to play him in "Straight Outta Compton" was sheer brilliance -- not only for the movie, but for their personal relationship ... and we got proof straight from father and son in NYC.

O'Shea Jackson Jr. and Cube were doing some promo work for the flick when our photog asked Junior what's the most interesting fact he learned about his dad while shooting the N.W.A. biopic.