Ok, I'm a UT grad and I think these "parties" are stupid. There wasn't any of this back in my day. Granted, that was a very long time ago. Sororities do not need these to attract members.
It's not to attract members, it's to repel the possible members they do not want. Also to mark their claim on the possible members they do want, even if those possible members don't agree.
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It is all 33girl's fault. ~DrPhil