Considering you were using a drill at the time, this FML could have been a lot worse.

Hey Darryl how it hanging!!!

Low, loose, and full of juice!

Aaaaand lawsuit.

 Is the drill ok?

That's about 6 meters.

Or in practical terms, about 2 and a bit floors. That is frigging high to be left hanging on for dear life.

The level of FML depends on whether your coworker is merely clumsy or is actually trying to kill you

That's horrible!

That's a firing offense, isn't it? NO company wants an employee that deliberately endangers the safety of other workers like that.

I hope you got his ass fired

Personally, I would speak to the boss about this and let him know what happened. I am sorry you went through that, but this is very dangerous and you could have been really injured. More than just dead arms, you could have hurt yourself with the drill or falling. I think you need to tell someone about this and make it very clear that you want something done about it.