Marmaduke is terrorizing a Parcel Delivery (TM) employee in jest.

Marmaduke has learned to move as fast as the characters in The Matrix. He is using this newfound ability to exasperate his owner-lady (who, for reasons still at large, is dressed like a Quaker today) while she cleans a window.

Marmaduke's owner-lady is guilting him into not killing her for trying to give him a bath.

Special "Choose Your Own Level of Anthropomorphization" Edition

Marmaduke is an aggressive and enthusiastic debator, regardless of what issue is being discussed, or which point of view he is arguing against, or the fact that he cannot speak a language.

OR

Marmaduke is barking at a couple of guys for being loud.

Marmaduke is staring down a fortune teller, daring her to say something negative about the future of dog food and incur his fearsome rage.

Marmaduke is a terrible fucking comic strip.

Marmaduke is an asshole.

Marmaduke's perceptions regarding how he is to be treated match up perfectly with his owner-lady's facetiousness.

Marmaduke is forcing his owner-lady to buy a car large enough to comfortably fit him and all of his bastard children.

Marmaduke is going to murder a squirrel for disrespecting him, just as soon as he can figure out how to climb a tree.