My buddy/instructor always picked on me..knocking gear off, knocking regs out, etc. I got used to it. Later on, on the occasion something actually happened, I was able to just deal with it as if it was nothing.
NOTHING prepared us for another buddy that went into a full blow panic at the bottom of a 100ft Cavern. He took off for the surface, and my instructor took off after him, holding him down finally at a certain point just to not get an embolism and slow him down. He kept putting the reg in the buddy's mouth, but the buddy kept spitting it back out, there was no stopping him from surfacing. Finally he was able to get him controlled to the surface enough not to get an embolism.
The buddy later wrote a paper on it afterwards on everything that went through his mind, his entire thought process, etc. It was a very interesting read. This buddy is normally always calm, collected, chill.. he never gets upset or panics about anything. But this small sequence of events that happened in this cavern that day just set something off in his mind and there was no way he could stop it. He said it was very strange fighting your body...it was going to do what it wanted to do, and would not take no for an answer. He said he knew what he was doing, but could not control it. Panic is a very interesting beast.
He had some water in his lungs for a bit, but everyone was ok afterwards.
We learned a LOT that day from that incident and from the paper he wrote for us to read later.
Moral of the story is... you just never know what will set you off, when your time will come, what your threshold is until it happens.
Just being prepared with redundant equipment, having a buddy with a level head close by, and practicing for anything you can will help... but may not always be the right thing when you need it.
