Wow, what a lot of posts. I have to say that I am somewhat dissappointed about the poor quality of insults flying about. If you're going to do it, you really ought to try and do it properly. Here's a few ideas to get you going.........
"Thou art a boil, a plague sore, an embossed carbuncle in my corrupted blood"(King Lear)
"Poisonous bunch backed toad" (Richard III)
"There is not yet so ugly a fiend of hell as thou shall be"(King John)
"There's many a man hath more hair than wit" (Comedy of Errors)