'Workaholics' Star -- Fractured Spine After Roof-Jumping Stunt ... On Tape

Blake Anderson -- the frizzy-haired guy on "Workaholics" -- fractured his spine Saturday night ... jumping off his roof onto a beer pong table ... and the incredibly stupid stunt was all caught on tape.

Sources close to the actor tell us, he's currently undergoing surgery to treat the fracture -- and fix whatever else he messed up. Needless to say, he'll be out of commission for a few months.

Blake was throwing a party at his L.A. house when the accident went down -- attended by Tyler the Creator and members of his rap crew. We're told cops shut the entire thing down not long after the roof-jumping.