Oh, I thought it stood for something like "Priority Denied Boarding," which sounds like a typical DL dehancement. I have always referred to the drinks as "Pre-Flight Beverage (PFB)."
I do enjoy that feature on DL, although it seems to be disappearing since the merger with NW. I'm sure I'll manage somehow.
I think I'm going to jump on this cheap F fare on AS. I will get full 150% MQMs on DL for it.