Made me think of Eddie Izzard's evil giraffe clip

You really need higher cognition for that, although I will grant that even cats on the higher end do understand that they are not supposed to be doing the thing they're about to do and will simply wait for you to look away or do it really really fast. They're just not capable of any greater evil that isn't running across the dinner table.

So now the question becomes how dedicated to evil does one have to be, in order to be evil? Does a life committed only to scratches and bodyslamming others out of the way of free food count, since it's a life committed only to selfish pursuits?

.....I'm pretty sure I had an evil cat once.