Any thing under tension....
Amen to that. Still scarred by an incident over forty years ago, when I stood on the front of a narrowboat stuck on a sandbank, paying out a rope to a kind passing boatperson which offered to tow us off. Attached rope to the front of our boat, then handed other end to kind boatperson, who attached it to their stern, and set off. Rope gradually emerges from water (therefore dripping wet and even heavier), staightens, tensions, then abruptly detaches from rear of other boat and flies directly back at me, impacting between waist and mid-thigh.
Good thing I never intended to breed.
(Facepalm icon because it was a "D'oh" incident, but also because there's never a crotch-palm icon when you need one.)