Skateboards are really REALLY dangerous ... so says a Lil Wayne fan who claims one of the rapper's goons grabbed one and bashed him in the head with it back in May ... and now the fan is suing.
The man on the receiving end of the attack is Alfredo Marino -- who claims he spotted Weezy on the streets of L.A. last year and tried to take a photo.
But according to Marino's lawsuit, filed in L.A. County Superior Court by attorney Craig Chisvin, a man who works for Wayne grabbed a skateboard and clubbed him in the back of the head.
Marino claims he suffered a severe injury to his melon from the incident -- and is pointing the finger at Wayne and Wayne's record label because he believes they were responsible for enabling the attacker.
Marino is suing for unspecified damages. Calls to Wayne's camp have not been returned.