Jaleel White -- Kentucky Couldn't Handle Hollywood ... So UCLA Kicked Dat Ass

Jaleel White knows exactly why #1 Kentucky turned from Stefan to Steve Urkel Thursday night against UCLA ... the bright lights of Hollywood ... saying the boys from Lexington simply couldn't handle the big spotlight.

Jaleel was leaving Matsuhisa restaurant in Bev Hills last night when we asked what all college bball fans are wondering right now ... how the HELL did unranked UCLA upset the #1 team in America?

Check out the clip -- Jaleel ... who is SUPER PUMPED about the victory ... says there was a Staples Center atmosphere in Pauley Pavilion last night -- tons of celebrities -- ... and Calipari's crew buckled.

Now if it only worked in the NBA ...