The following interaction took place at a recent gig we played, where the rabbi was trying to move the proceedings along while the guests were still chatting and indulging at the buffet.
Rabbi: We are now going to bentch!
Guests: Yap, yap yap!
Rabbi: Bentching is starting RIGHT NOW!
Guests: Yap, yap yap!
Rabbi: No one is being forced to bentch! But we do ask that you remain quiet!
Guests: Yap, yap yap!
Rabbi: PEOPLE, PLEASE!!!
Guests: Yap, yap yap!
Rabbi: THE WAY YOU'VE EATEN, YOU ARE ALL REQUIRED TO BENTCH!!!
Guests: Yap, yap yap!