David Cassidy You Dumb, Stupid Idiot ... Turn that Light Off!!!

10/30/2016 9:24 AM PDT

David Cassidy Yells at Fan, You Dumb, Stupid Idiot ... Turn that Light Off!

EXCLUSIVE

David Cassidy wore his medical alert bracelet on his sleeve Friday night, going bananas on a fan who ignored his considerable ailments just to get a little video.

The 66-year-old former Partridge Family star was performing at Hudson Valley Theater in Peekskill, NY when a fan shined a cellphone light smack into his cornea.  

You gotta watch ... David somehow thinks people know he's had 5 eye surgeries and counting, and issues an ultimatum ... eject the dude or he won't continue.