The Monty Python team have come up with some good ones. From the Architect sketch -

"That's the kind of blinkered, Philistine pig-ignorance I've come to expect from you non-creative garbage"

And of course the French insulting the knights in 'Holy Grail'

"I wave my private parts at your Aunty."

"Your mother was a hampster and your father smells of elderberries"

:-)

But my favourite is not so much an insult as a curse - Apparantly translated from one of the Arabic languages.

"May the hole in your arse heal up."

Eeeeuccchhh.

:D (tG)