"You clinking, clanking, clattering, collection of coliginious junk!"
The Wizard Of Oz
"If there was a retarded Oscar you would win, hands down."
Sam, Garden State
"If there's a mental health organization that raises money for people like you, be sure to let me know."
Frank Sachs, As Good As It Gets
"Does Barry Manilow know that you raid his wardrobe?"
(Obviously, an '80s precursor to: Barry Manilow called, he wants his wardrobe back.) 
John Bender, The Breakfast Club
"To call you stupid would be an insult to stupid people! I've known sheep who could outwit you. I've worn dresses with higher IQs, but you think you're an intellectual, don't you, ape?"
Wanda, A Fish Called Wanda
Can't take credit for remembering all these. Got them from a randome movie insult generator at virgin.net