It was my trusty Nikon FG (going strong for me since 1984). I was changing the aperture ring (not using compensation) so it would simply change the shutter speed to match whatever I set and deliver consistent exposure.
My most recent mishap was trying to wind film on a 35mm spool backwards, fortunately didn't kink it too bad before I realized what was going on. I've always had the feeling I would do the exact same thing with the tank lid too, so to avoid it and keep it from leaking, I always give it a wrap or two of electrical tape.