[Next_rim]

I don't see how rephrasing the regular adage helps emphasizes your point. Isn't the original accurate enough?

Smashing stones with a biologically produced mass is to a certain degree harder, than killing a fragile living creature with a stone. Thus, rephrasing is not only humorous at some angle, but stresses the difficulty of the underlying task, and how the method proposed accomplishes the seemingly impossible. I personally find the rephrased version absurd, thus funny, but still carrying some wit. Feel free to disagree, I don't care as long as you get my point