no disrespect to the young guns on here, but I did a few stupid things around age 15-16. I had a 55 chevy. with a 283-four speed. I needed to work on the rear end, i used a bumper jack that went with some other car to jack it up. no jack stands, no blocks, nothing. i crawled under it did what i needed to do. ( forgot what it was now ) crawled out and walked over to my tool chest, as i turned to go back to the car, it slowly rolled backwards, and fell off the jack , i didn''t even cross my mind that could happen. needless to say, i would have been mashed like a bug, but I was 16, my mindset at that time was i can''t get hurt to bad, and i damm sure couldn't be killed. GOD was watching over me !!!!