For me it was something I stumbled upon at my family's mountain cabin. The toilet pump was going bad and needed to be replaced, but after a flush and the tank would refill, if the buoyancy and position was JUST right it would create the most god-awfully ear-bending (more like ":makes your ears fold back on themselves and implode), harmonically-pure ring. I've designed my share of tinnitus/hi-freq ringing moments - the sound of this thing has nothing on them). The position and bouyancy had to be so precise that I set up the 702 and spend a good 15 minutes gentle moving its position millimeters and centimeters and carefully applying pressure until I could find the sweet spot and hold it for a few moments.
Managed to finally get a good 15 sec steady which can be looped relatively easily, and it's now one of my go-to's when ear-bending tinnitus is needed.
Captured in 96k, in hindsight I wish I was recording it 192 with something like an 8020 or 8040. Would have been epic. What impressed me the most was that it slammed up against the limiters hard but they took it like a champ, no audible distortion or artifacts.
Seriously though, it hurts after just one or two listens!