People are pansies these days, and can't take a good insult.  I am one of those pansies, but that doesn't mean I don't like to dish out the pain.  Embracing hypocrisy: it's gonna be huge in '10! 

One of my favourite insults comes courtesy of my beloved pops, who gets his chuckles calling people "dirty Ruskies."  Kids these days are too stupid to know that Ruskies means Russians, and therefore commies, so I just cut out the middleman and call people filthy communists. 

WHAT A LOSER! AHAHAHA

D-bag is also effective--even Tracy Jordan agrees:

Scumbag money grubbing future lawyer can be fun if you're needling your law student boyfriend, but expect tears, so tread cautiously.

LAWYERS ARE JERKS, AMIRITE?

I can't do all the work for you lazy bastards.  You get the idea.