Back when I use to be a bouncer I tripped over a chair while breaking up a fight. Two guys were wrestling/fighting on the ground and I grabbed one to pull him off the other. He turned around to punch me and I instinctively stepped back and into a chair they knocked over. I fell backwards and landed hard on the legs of the chair, which really hurt. After I kicked them out the bar staff asked if I was okay as they saw me fall and I had to admit I tripped over a chair...they laughed.