When the cat’s away, the mice will play! An expression that works just as well for animals as for humans, apparently. Because when humans are not there hunting them or trying to pet them, animals come out of their hiding places and let loose in ways that can only be described as, well, bizarre! And it’s not in wildlife documentaries that you’re going to see this kind of behaviour. Here are 18 photos taken in the moment by patient photographers with hidden cameras.