Chairman-
"including DMs turning off my air." We were warned about that, and "anything goes" during harassment day during training. Anyone surfacing before their tank was empty, would be flunked. So I'm hanging out in the deep section of the pool bottom, trying to keep one eye behind me head and just be situationally aware, when one instructor swims over, doffs his gear, and motions for me to hold it for him as he goes away for do some forcible buddy breathing. No octopuses then either.
And I get to thinking, anything goes? OK, fair's fair. So I bleed the instructors tank dry. Still no sign of instructor. SO then I also TURN OFF HIS VALVE. Figuring, he'll quickly realize the valve was turned off and patiently turn it back on, only to find, heheh, a bone dry tank.
You know, when someone gets really pissed off about not having any air, you can hear them screaming curses, all the way down through the water?(G)
I hope our instructor is still alive, because I really ought to get around to sending him a thank-you letter, for teaching us "DON'T PANIC" long before Fedex or Douglas Adams made that popular.
His philosophy was that it is VERY easy to get killed diving. But that for every possible failure, there are THREE ways to get past it, and if you don't panic, but just run the 1-2-3 ways to get past it, you'll only be inconvenienced, not dead. (That, and that some people are naturally panic-prone, and it was an instructor's job to just flunk them out and convince them to take up something like golf instead.)