Ya i have heard of many people getting crushed threw the years by just using a jack. My father growing up in the 70's always worked on cars and would just crawl under with just a jack some times, most of the time he used ramps though. You will not find me getting under a vehicle without jack stands under it or if on ramps the rear wheel chocked.

Always have had a thing about getting under all that weight anyways. LOL so some times I probably go a little far in supporting it.

 

^ + 1 on that dude! ^

My uncle got a car dropped on him but lived to tell. Lucky someone heared him yelling consitering he was by himself.