snap bids

Snap bids depend on if a house has pledged total or not. They are determined after the pledge lists have been compiled, very early in the morning of bid day (think 5 a.m.- yes, Panhel officers are up all night). The sorority is informed, and then they decide if they want to snap bid. They make calls and invite women to join....or sometimes no calls are made, this all transpires with enough time to add the person to the bid list.
Only a handful of snap bids are issued, despite the rumors you've heard. Often the other sorority members and certainly the pledges have no idea someone is a snap bid, since they come in with everyone else. Generally, only the involved officers know, and sometimes the new member.
There's no way of knowing how many are given, since it's different every year. New row houses do them, but it's no unheard of for old row houses to do them. But usually it's only two or three groups every year that wind up doing them.

Phi Mu did a few years ago, but KD does it consistently every year