Must keep scenes

[Karen]

I've been re-reading HBP and all I can say is no matter what, they HAVE 
to keep the party scene when Luna tells Slughorn, Harry and Snape that 
the aurors are trying to bring down the MoM by a combination of Dark 
Magic and gum disease.  That has to be THE shining moment in JKR humor 
and will make for a Rickman expression to bring down the house (along 
with Harry choking on his mead). Are there other "must keep" scenes 
people can think of?