I was jacking up my mustang so I could change the oil. When i put the jackstand under the rear of the car, I started to remove the jack. Apparently, the jack stand was slightly off center and it flew out as the car went down. My shoulder was still under the car and the wheel well hit my shoulder on the way down. At first, my shoulder was numb and I thought i broke it or something. After I started to move it around, it hurt but overall I was ok. I never went to the doctor but I'm guessing I tore something because it hurt to move it for a while. Definitely scared me though.