Danzig -- I Said, NO PHOTOS!! Puts Fan In Headlock (VIDEO)

Metal legends Danzig have a strict no photo policy at all shows -- and failure to follow said policy will get you a quick ass whupping ... as one fan just learned in Southern Cali.

The fan either had massive balls, or was just plain insane ... 'cause he started snapping away with his smartphone during Danzig’s Pomona concert last weekend. Lead singer Glenn Danzig quickly snatched the phone, but the real pain came post-concert when the attention-thirsty idiot tried to get on Danzig's bus ... WITH A CAMERA!!!

He was asking for trouble, and got it in the form of a headlock from Glenn. The video is crazy, and if the fan looks familiar -- his name is Navid Farsi ... the dude who sugar-bombed Adam Levine in Hollywood.

Unlike that incident, Farsi did NOT get charged for the Danzig scrap.