A few months ago, Alan posted a sign on his office door (at kitty height) in his almost illegible scrawl, saying "No cats allowed." He'd been having trouble with one of the cats spraying stuff. I gave him a really hard time about the sign. My attitude was that even if cats could read, they wouldn't let a sign stop them from doing anything they wanted. The sign stayed up for quite a while and whenever one of them would attempt to cross the premises in Alan's presence, he'd point at the sign and yell at them to get out. Yesterday, I found the sign down the hall in the bathroom with a big yellow spot of pungent cat pee on it.