REPORT IT TO YOUR GREEK ADVISOR. Get the guy who was bidded a day early to tell him/her about it. If you can find guys who were given alcohol by that house, get them to tell the Greek Advisor too.
This would happen in a perfect world. In our not-so-perfect world, the same houses that dirty rush are the ones that everybody wants to be in. Those who are dirty rushed are never going to tell on this house that was good enough to let them in. Same thing happens on my campus.
