Marmaduke is an asshole.

Marmaduke's owner-girl thinks he has the lawn mower confused with the vacuum cleaner. In reality, Marmaduke has the lawn mower confused with a serial rapist.

Marmaduke's owner-man mistakes him for the neighborhood trash can inspector.

Marmaduke is trying to let his owner-lady know that he wants to fuck her. His innuendo may seem blunt and crude, but in his defense, he is a dog.

Marmaduke frightened a little boy named Jeremy simply by playfully growling at him, and having jaws large and powerful enough to snap a little boy's torso in half.

Marmaduke is being defended by his owner-lady for a very drawn-out yawn, the force and/or volume of which caused his extremely hungover owner-man a great deal of physical pain.