Trey Smith Little Willie Style ... Woo, Ha Ha!

7/10/2014 6:00 PM PDT

Will Smith's firstborn son co-starred with him in the "Just the Two of Us" music video -- but we hadn't seen much of Trey Smith since then ... until our camera guy bumped into him in the Valley.

Trey's not nearly as famous as his dad -- or his little siblings -- but check him out ... still an awesome guy.