The other day I ran across a reference to the Shakespeare Insult Kit, which offers two columns of adjectives and one column of nouns that you can precede by “thou” (or “you”) to create some colourful insults. If the characters in your novel or screenplay are calling each other boring names, this could be a life-saver.
Some of the juicier adjectives:
And outstanding nouns:
These could also offer some variety to your everyday language. I don’t think you should insult a traffic warden for doing his or her job, but if you couldn’t resist, think of how satisfying it would be to shout “You artless beef-witted bladder!”
(Do you want friendly guidance on writing your book or screenplay? You'll find it in "Your Writing Coach," published by Nicholas Brealey and available from Amazon or your other favorite book seller.)