I usually look at the asker with a confused, wide-eyed look and say, "Of course, why wouldn't I be?"
Actually conversation with a adrunken, obnoxious neighbor:
"Whhhaaaaat? C'mon, are you still doing THAT?"
Me (with a serene smile) "Of course I am."
"Well, you've just got to STOP that"
(calmly) "Why?"
I played around with completely turning her questions around, and she couldn't come up with a logical reason. ("They for your HUSBAND!!" "Um, actually they're wonderfully multi-functional."

)
I just field questions calmly and almost always just turn it around.
