I had the exact samething happen to me, thought it happend a little differently. We were working on my sisters car and my brother started jacking the car while i was under it. one of of the jackstands must of have shifted because when brought the car back down the jack stand fell and the car came down on my chest. Luckily im a tubby basterd and i walked away with nothing but a big bruise but yea i can definently feel ya on this one lol