Basically someone crazy. Kind of a synonym of "freak", but there is no humor in calling someone a freak, so if you want humor, call them a freakasaurus.
Freakasaurus was also mentioned in episode 15, season 2, of Star Trek: Voyager.
Freakard is gennerally refered to those who are freaky and retarded at the same time. People who have mantality problems and have unusual fetishes are usually referd to as this.
guy 1: hey howz it goin?
guy 2: nuttin much, u?
freakard: hiala look at mi lint culecsion.
guy 1: uhhhhhhh, go away freakard!
freakard: nuaa oooooook.