[That's for the best, this is definitely no real good time for joking at him. He has a better sense of humor than most may realize, but there are limits.]

It's the first explanation I could come up with. It's not as if... [He pauses, trying to get at an especially annoying area on his back. Ahhhh... got it, that's good... He lets out a sigh of relief.] ...as if I've encountered anything unusual recently to cause it. Unless there's some foul magic at work. I haven't ruled out that possibility.