Real diving mishaps please

[arcFlash]

So like MaxFactor said the board is kind of slow and I've been reading a lot of stuff about diving and I have some questions about books and real diving.

Running out of air is always listed. What the hell are people doing running out of air! I don't consider myself very experience (70 dives) but at this point I can't see ever running out of air. I monitor my SPG, I rig my gear carefully, I carry cutting devices, pony, buddy ... So can anyone share a first hand OOA story and how to help me understand how this can happen to experience divers who try and do things by the book?

Second question: Has anyone ever flashed the OOA signal to their buddy to get a real test? I did once and they freaked, I would have had to pull the octo myself had I been able to get to it. (I'm a long hose fan and we did work on that skill) Is this fair to do without pre-dive warning? I wouldn't mind as you don't get notice in real life.

Third: Whose been tangled up? How did it happen? Did you learn anything or make gear changes?