This is perhaps one of the most overplayed tropes there is. It has birthed a Dilbert character, a classic Onion headline, a far too old meme, a good comic (last time i checked anyway) a bad comic, and god knows what else.
The "It's all a dream!" plot is also overused, at least in xkcd. There was that school nightmare one, there was that piratey one? There was this one, and like before, there's probably more that I can't find right now. feel free to add things.
Anyway, this comic is just another crappy "Cats! what if they were EVIL??" joke. These are nearly impossible to do well, and this comic comes nowhere close.