The gimmick is simple. "Garfield" comic strips with Garfield the cat removed. What remains?
[...]the existential angst of a certain young Mr. Jon Arbuckle. It is a journey deep into the mind of an isolated young everyman as he fights a losing battle against loneliness and depression in a quiet American suburb.
Poor Jon. He is profoundly depressed, schizophrenic, and lives with a poltergeist. If only he had a companion, perhaps an animal of some sort...
UPDATE: the Tubes win again! No copy of the comics can go here, so make with the clickity-click.