Maybe not THAT extreme, but I did bury my hydrophone in my compost pile. It's out on loan, but I figure I'd need to let it sit for a few days before recording with it, and then would need to do so for a few hours to see what I could get...the initial session was too short to get much cool stuff.

While I take no credit for doing it, an old friend of mine submerged one in his bathtub and fired off a bottle rocket. Him, the mic, and the bathtub/apartment survived.

Maybe a bit more of a joke... but this dog was seriously psycho! And it obsessed over the fluffy a little too much. Got a few nips too. The sound was was what I needed so it paid off.

oops, just read "hydrophone" in the title... I always post quicker than I read. In anycase it was so slobbery, that I probably needed a hydrophone.

I tried putting the hydrophone inside a balloon filled with water to get interesting impacts, jiggles, etc., but unfortunately I couldn't figure out a way to avoid cable vibration/noise emanating from where it touched the tied neck of the balloon. Made some interesting sound though.