I was working on a crew building patio homes, we had just put in the wooden beam across the opening of a garage. I was nealing down nailing the studs in that hold up the beam when the guy on the scaffold above me dropped his hammer. He yelled, "look out", I looked up just in time to catch it just below me left eye.
The other time we took lunch break and someone left a cats paw nail puller on the plastic tray on the top of an 8' stepladder. After lunch I needed the ladder, I leaned it towards me and folded the spreaders and got the bar on the dome. It wasn't a good week.
The same thing happened to me except with linesmans pliers. I always check the top of the ladder first now! Some people i work with cant be bothered to keep their tools in their tool pouch.
Did that to mine not long ago. I pulled a total dumb@$$ move and didn't check to see if the bolt was locked back before I pulled the take down pin. SMACK. No more retaining pin. I bought two when I replaced it.