The old Beetle jack was not threaded. It more resembled an old time bumper jack but without the notches and relied more on prying the car off the ground.
It had a square peg on the jack that fit into a square hole in the car and no way could it turn either direction on you. It was also very easy to operate, even in the dark on the side of the road.
This is what they look like.
http://cgi.ebay.com/V-W-Volkswagen-Bug-Beetle-Original-Jack_W0QQitemZ300165253666QQihZ020QQcategoryZ10781QQssPageNameZWDVWQQrdZ1QQcmdZViewItem