ROL! Cats are ingenius! We have a little doggy door for our cats but they have to come in at night. We left for a 3 day jaunt to my folks' and when we got home the cats were out! But we had locked them in!!! Discovered after that happening a 2nd time that one of them could open the doggy door ONE way but they couldn't get back in. The last time there was no evidence of them eating or using the litter box --- so we figured they'd gotten out the first day. Unfortunately for the, it had SNOWED while we were gone. DH has fixed so they can't get out, but they won't go out in the mornings until they're SURE that door is unlocked now!!! LOL