Where a person named Jon makes a comment which makes absolutely no sense to anyone but himself.

v. collectively or individually finding someone/something to blame for a problem, as opposed to brainstorming which connotes finding solutions to a problem

n. the act of finding someone/something to blame for a problem

(from a TV ad for HD television)

The word used to describe all the ridiculous/stupid actions or phrases Jon Arbuckle says in the hit comic strip, Garfield. Typically, the higher the jonsense, the clearer it is that the cartoonist Jim Davis is running out of fresh ideas.