"Dude, did you see what Bill did last night? He tripped over his pants, knocked over a lamp that fell on Joey, and he yelled at Joey for making stupid noises. He is SO douchetarded."
An insulting term for someone who is simultaneously a "douche"
(i.e., an asshole, jerk, jackass) and a "retard." Expresses both unpleasantness of personality AND stupidity at once.