Years ago at a small company we suddenly heard a puppy loudly, desperately yelping.

We looked around a little bit and soon discovered it was inside a locked closet.
We were still trying to find a manager with a skeleton key when the puppy owner showed up.
It turned out he was doing some work on our roof and had brought his new puppy along. Somehow the puppy got into the spaces and fell into the closet which of course was pitch black. Fortunately the dog wasn't hurt but it was about as scared as an animal can get. Ha, ha I guess.