It is the combination of the word autistic and goober, because that way, it sounds nicer.
Also referred to as moonpie and that one kid you are nice to only because you think they'd kill themselves if they had absolutely no friends and that one kid whose face would be broken if you weren't such a nice person.
Girl #2: He did not! Did he?
Girl #1: Yeah! I know, right?
Girl #1: Oh my gosh, he is SUCH a moonpie.
Girl #2: I know, a real autogoober.