I was just reading through 1 Sam. 5 again, and for some reason this time, it struck me as weird. I had never considered just how weird God's curse of hemorrhoids was. Now, it's certainly probably not the weirdest thing he has cursed people with, but I have never considered it.
There are some practical reasons why he might--they are a war like people, and you can't have soldiers with hemorrhoids hobbling around the battlefield in heavy brass, maybe even some mixtures of iron, armour.
However, the thought occurs to me in how symbolic the surrounding context is. It is very intentionally orchestrated; first from the curse of Eli so that no man would miss it, but also to begin equally as grand to inundate Samuel's prophet-hood. The Philistines, of course, set the Ark before their god, Dagon, thus symbolically showing the superiority of their god being literally above the Lord.
Rather than being forward or complacent, the Lord then tumples over their idol--a message I take it as saying he is fallen over and needs human aide to get him back up, where the Lord needs no human aide to take care of the Ark where he rests, but also to force Dagon to bow before him. But, of course, he made it nonchalant so that none would connect two-and-two. Then, of course, he knocks over Dagon again, this time decapitating him and removing his hands--a clear display of dominance.
This is very spiritually significant clearly, in its symbolism. So, I also wonder, is there anything that we know of to why he would opt to curse the Philistines with Hemorrhoids? Perhaps like a folk superstition that is a curse of their gods or something? just a thought.