Jamo
I know how ya feel. I banged my head once or twice on those quickjacks and I must admit that I have wacked my shins several times on them also. However the worst pain I have suffered from them was once trying to get from under the front of the car while not being quite clear of the quickjack as I went to get up, all the time with one arm still part way under the car holding some tools. You haven't experienced pain until you have securely stuffed the soft part of your upper arm into the bottom of a quickjack. I am much more careful now.
Wayne