This is a common misconception. The truth is yes but a lot of things would have to go very wrong to make it possible. It is possible for a fly to stop a freight train. The fly, however, would need a velocity 6 orders of magnitude faster than the speed of light to do it. But back to the first question, yes but not really. Chiropractors train carefully in technique and anatomical knowledge to minimize risks to the patient. Because of our extensive training there is no way for a chiropractor to accidentally apply the amount of necessary force at the necessary angle to dislocate a head.