4) Animal House (yeah, that one's a gimme
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5) KEGhouse was Steve's fraternity on "Beverly Hills, 90210"
8) Revenge of the Nerds, TigerGirl is right
9) I have not seen Van Wilder, but I'll tell you where these letters appear: In the movie "Can't Hardly Wait," Jerry O'Connell (who has grown up to be quite a nice-looking young man, if I do say so myself) made a cameo as a former high-school football player, and he was wearing the letters Delta Iota Kappa on his shirt
And here's one from literature: Pi Beta Alpha. Hint: think fluffy teen books. A cookie for the person who gets it.