This happened to me when I worked a summer at McDonald's. I was walking to the front register, past the french fry bin, and slipped on a greasy spot on the floor. I put out a hand to catch myself, and slammed into the side of the fry bin, smacking my ribs.
My arm was in the bin (mostly empty, fortunately), but it was hot, and I tried to extricate myself and somehow wrenched my arm and chest muscle on the right side, before I finally collapsed against the fry bin. I couldn't get any traction on the greasy floor.
I went to the ER for a chest X-ray, but no rbs were broken. The doc said I might have bruised a rib, and had certainly strained a chest muscle. It hurt like stink for a few days, but I survived. Not interested in a repeat incident, though.