Was listening to CW and Blum talk about not knowing what '801 day' is, and specifically not knowing the origin of the name. 801 day occurs on the Saturday before classes begin. As far as I am aware, the name originates from the sorority ban on drinking for the entirety of the week leading up to the Saturday during sorority rush. The ban is lifted at 8:01am on that Saturday, hence the name and the extravagant 'extracurricular' activities.