How did you know?

One of the rules in our house that seems kind of dumb from the outside is "no cats in the bathroom with you". Poor Farlow and Boogerhead have enough to deal with without being trapped in the bathroom with people.

Another is "the bathroom is for going to the bathroom and getting dressed - not for playing"

This morning, while one of the boys was getting ready, I got up to get a drink for Manasseh just as the other boy was getting out of the bathroom and I saw both cats were inside. I asked him "why were the cats in the bathroom with you?". (Obviously the child was playing with the cats in the bathroom). Child said "How did you know?"
I did not choose to reveal my sources of information, rather let the child be amazed that I found him out. My oh my...how did you know. I have eyes child, eyes!