For me, it was Nuclear Biological Chemical defence - chemical appreciation exercises.
This was back in 1999. Corporals were always in a mood with the standard we were in ( I was sporty and smart, but no street-smarts at all), so we used to do respirator drills with riot control gas, but 4 times as concentrated as it was supposed to be and then do exercises in the hut (it was the same size as a garden shed or a large lift/elevator).
The morning would be a night mare, either drill or PT, where inevitable someone would balls up and then they would state how many (illegally) tablets they would put in.
It got to a head eventually. One lad freaked out in the chamber and then the Corporal tried to take it out on all of us, he tried to get me in a head lock, so I punched him in the gut, ripped his mask off in the chamber and then ran away.
I was convinced I would get charged, but looking back it would probably be too much explaining to do if it went in front of the Squadron Leader.
I've had more worse things happen which could have affected me more, such as being sat in Brize Norton waiting to fly out to Bosnia or Iraq (both times alone, as I had to back up other units as an individual augumentee, which meant I met them in theatre).
A few months ago I got into a really bad car accident (No, THIS one was not my fault. Really! What? I'm serious. Why are you all looking at me like that?). The other car drove right into my passenger side and my car spun. Luckily it was a side road and not a highway, and there was nobody coming on the other side of the road. If there was, I would have crashed head-on with another car. I wound up on the grass. Luckily, I didn't crash into the tree. Just to show how bad the accident was, the other driver's insurance had to pay the cost of over $5,000. I was more surprised at the time, but after it all happened I realized just how lucky I was.