Scene: I'm in the shower and Ben comes in to use the toilet. He pulls down his pants...
Ben: Where's my underwear?
Me: Didn't you put some on this morning?
Ben: I don't remember. Maybe it fell off.
Me: Go put on some underwear when you're done.
That happened the day after this: He didn't want to change out of his dirty underwear, so he just put the clean pair on top. I didn't know until later he talked about having on two pairs of underwear. I checked him, but he was only wearing one. Later I found the other pair on the bathroom floor. When I asked him about it he said, "Maybe a ghost brought it downstairs."