Yes, if you read the book version of Legally Blonde, Elle's a DG. And in Eating the Chesire Cat, Tri Delta is prominently mentioned. :p So it doesn't seem like there's any restriction on using GLO names even in less-than-positive portrayals. However, I think most writers don't want to risk the fact that they could possibly be sued for libel if they portray real sororities or fraternities in bad ways, so they make up their own names.

the gentleman who created the simpsons is a sigma chi. the sigma chis at my school used to arrange their meetings so they could watch the simpsons before. i agree with sugar and spice that the names are changed so people won't get sued. But I still have a question (maybe sugar and spice) can answer. Why on Saturday Night Live did they have skits about Tri-delta (and one had a TKE in it)?

If I recall, Saturday Night Live DID get sued for the Tri-Delt skits. The guys who wore fraternity sweatshirts (Rob Morrow and John Goodman) were actually a TKE and Sig Ep.

Did they win though? Or even close? You can sue over anything but winning is a little tougher.

Think about all the movies that portray numerous organizations one way or another. Anything based on this world is going fictional membersof organizations.

I rememger that Happy Days episode. Richie's girlfriend was a DG in the episode.
And Legally Blonde used the DG crest with a slight variation. The foyer of the DG house at SC was used, I believe. Maybe some Alpha Nu Chapter sisters can verify??

I was waiting for someone to bring that skit up. The infamous "Delta Delta Delta, can I help ya, help ya, help ya?"
I have no idea why they used Tri Delta's name, or if a writer was one or something...but I have come to realize where ever I wear my letters, someone will either say it directly to me or say it just loud enough for me to hear.

Yes I believe you're right. I was told that Reese stayed with the DGs and also the Kappas before filming Legally Blonde

I know (or at least am very certain) that she stayed with the Kappas before filming. I was told that by the official Kappa colonization presentation. :)