Two and a half years ago. A belligerent resident hopped up on meth. To be fair, he wasn't exactly aware of what he was doing. It took three of us to bring him down to the floor in the hallway. He continued to struggle and scream (about spiders in his hair) until the cops and the ambulance showed up.
If you mean a dick-swinging kind of physical altercation, never. (I'm sure that one will please the crowd.)
Any visible scars you would rather weren't visible?