Probably for me, it was the AGR testing place, back of ROSARIO Block in HMS DOLPHIN. I seem to have climbed into a coffin (that was supported by 2 x trellis), complete with my A.G.R. (or S6 - whatever it was called and promptly lapsed into an alcohol-induced coma. The coffin was in the middle of the Gas House,and trainees had to march round it, before lifting the side of their gas mask and inhaling a bit of CS just to get an idea what it was like. Was rudely awakened by a JR "wandering willy" and the DSR, who offered me either (a). My own bed back in the block or (b) A quiet night in a room with bars on the windows. There have been other surprise wake-up calls, but I have only just remembered this one.