Lil Wayne -- Brawls with Ref Over Bad Calls ... In CHARITY Hoops Game

Lil Wayne got so furious at a referee ... in a charity basketball game ... he charged at the guy, allegedly SPIT on him -- and sparked a bench-clearing fight at a "stop the violence" event!

The brawl went down in St. Louis on Sunday night. Wayne's Young Money team was taking on a team coached by the event promoter, Loose Cannon Slim -- and we're told Coach Weezy thought the ref was blowing a bunch of calls.

In the video, Wayne is running after the ref with his whole crew behind him -- and the ref is wisely retreating into the crowd. Witnesses claim Wayne had already spit on the ref at this point.

TMZ has learned someone called police to report an assault, and although cops responded ... no one was arrested.

Again ... this was all so a guy named Loose Cannon could promote NON-violence.