I've just heard the funniest retort to a forum troll yet! This is based on the Frenchman dialog in The Holy Grail:

"I blow my nose at you, so-called 'best practises', you and all your silly programmer kaniggets. I don't want to talk to you no more, you empty-headed maintable-code writers! I Brice in your general direction! You mother was a function and your father smelt of CS degrees."

You can read the full thread here: http://discuss.joelonsoftware.com/default.asp?joel.3.559492.41

Made me laugh pretty hard when I read it. Good thing I wasn't drinking anything at the time.