OGRE to the rescue!
http://www.enworld.org/forum/dnd_view_block.php?id=992
You mewling, rotten turtle-lover! A basic insulter, medieval style. Not as florid as some of the Shakespearian ones - keeping it simple for the peasants! Now get to it you tedious, rooting blaggart!
Come on... isn't it more fun to make them up on the spot?