A person who attends college not only for an additional year (making them a super senior) but a year after that. Sometimes a super senior-ing is acceptable if a person needs this year for major requirements (engineering). With a sixth year senior this is not the case, it is pure laziness or unwillingness or stupidity keeping them in college. Possible reasons include the subject having a severe difficulty with launching or because they thought they were so cool in college they are scared of real life where people may not know them. It can also be a way to hold off being called an alcoholic (which of course only counts once college is over).
Person 1: Dude he graduated last year right, I mean he was already a fifth year?
Person 2: No, he's back for more. Super Duper Senior. Embarassing.