What's yours? You could include you favourite Blackadder line in general if it's not an insult.
Mine would be an insult towards Baldrick: "You're the worst entertainer since St Paul the Evangelist toured Palestine with his trampoline act"
Or: "I'd rather spend an evening on top of a stepladder in No Man's Land smoking endless cigarettes through a luminous balaclava"
And one for Aaron:
"We hate the French! We fight wars against them! Did all those men die in vain on the field of Agincourt? Was the man who burnt Joan of Arc simply wasting good matches?"
I think this thread is a good excuse to watch every episode of Blackadder again.