Is Sigma Nu an especially rapey fraternity?

[it]

I would actually guess that they are - there's a reason this sort of thing is shocking in the first place.

And seriously, as this happened to anyone? How often have you hang with a group of guys and see a passed out woman and they go "yay lets all take turns fucking her!"? I've been to parties, but I've never actually seen that. I have seen and had the opposite reaction - seen a passed out friend of ours and taking her back to her place.