A couple of days ago, I walked around the corner to find Collin very carefully drawing on the bathroom door. He was surprised when I asked him what was going on. It turns out that he was making a sign so that we would all know that boys and girls could use this bathroom. (Never mind the fact that we only have one bathroom right now.)
I explained that we don't draw on our doors, walls, furniture, etc. and we came up with a solution that we could both live with-for a while.
What a relief, now I won't be confused!