Spiders are a common fear, and it's not at all uncommon to imagine one lurking in your toilet, where your tender spots are exposed to things you can't see. That fear would be more prevalent in the days before indoor plumbing, when toilets were an easy shelter for wildlife. Thomas Morris uncovered an 1839 medical case from Pensacola, Florida, that might give you nightmares.
On the 7th of August last, Mr. Q. of this place, while in the privy, perceived himself to be stung by a spider on the glans penis. The pain, which was not great at the moment, continued to increase till 1 P. M., an hour after the accident, when it had become extreme, and I was called to see the patient. I found him lying upon a cot, and writhing under the most acute suffering.
Oh, it gets worse. Calling a doctor for such a malady was a mistake, because common treatments of the time were no help at all, and only added to the poor patient's misery. Fortunately, the patient survived, but probably never sought medical help again. Read the story at Thomas Morris. -via Strange Company
(Image credit: Trougnouf (Benoit Brummer))