I'm always impressed by how hardy fish can be. I hooked into a nice little 14"er a couple of months ago in a C&R area. Landed it quickly, but it took me a little while to figure out what was going on with that fish.
There was an extra fly attached to it that wasn't mine. The extra fly was attached to a line which was dangling from its poop shoot. When I pulled on the line that the fly was attached to, it pulled on its intestine. So, it seemed as though the fish ate a double fly rig and passed one of the flies and had another lodged in its belly or something.
I don't know, I trimmed the line off an let it go. It was healthy enough to be feeding, so not quite sure what the deal was. I'm just surprised how hardy they can really be.