Could be worse: I was just doing an oil and oil filter change on my car (just past 220,000 miles and running strong) and a hardened bolt is just sitting there in the engine bay covered in oil. I still haven’t figured where it came from, but have had no issues and have had it checked by others.

That good 'ol coffee ground emesis (spelling?).

One of my least favorite patients in the ER was a woman who had not returned in >4 weeks to get her stomache (post-surgery) looked at. She was rotting (and angry at us!) when she came in. It was my first really astoundingly gross experience.
My favorite was a man who came in who very obviously had regularly used drugs…