There's something about the juxtaposition between the series clean, almost Disney'ish animation style and the wild, crude and extremely wacky world of campus life that make this show irresistible. I spent a couple years living on campus and although my life in residence wasn't nearly as crazy, it was hilarious seeing all those recognizable characters--the stuffy RA, the pretentious know-it-all, that guy who really just doesn't give a damn. This series effortlessly clicks in and it makes watching it a blast.
Being a bit of a geek myself, I think the character I most enjoyed was Gimpy... Star Wars obsessed, will not leave the comforting electronic haven of his dorm room and so wired that his eyes have a permanent bulge. The scenes with him and all the loveable weirdos at Teckerson Tech were definitely my favourites.
If you haven't seen Undergrads yet, hunt down the DVD as soon as possible.