An irrecoverable condition marked by impulsive and prolonged lying. Generally, the subject matter is almost nonsensical and obviously bogus. The sufferer often uses this condition to make himself/herself appear supperior to others and at other times does it for no apparent reason.
John: "Wouldn't it be funny to drive a semi-truck to school?"
Justin (Griffinitis sufferer): "My dad already bought me one to drive whenever I ditch my learner's permit. I already put on some pimp spinners and it has a kickass system."