Plumbing

We are having plumbing issues tonight.  We don't know what in the world happened, but the bathtub refused to drain after the human finished her shower, despite everything that was done to fix it.  Do you think this could be some kitty act of sabotage?  But what would Brother have against the bathtub?  True, he didn't like to get in there, but he certainly liked to hang around outside and disturb the humans when they were trying to bathe.  Why would he want to break it?