A Few Old-Time Insults...

If you were on fire, I would not wet you with my damp underwrappings.

I quite like the modern version of this.

You hairy, pig-witted fox turd!

Well that's a picture, now isn't it?

May snakes crawl up your nostrils and feed on your tiny brain.

Nice, an insult and a curse, rolled into one.

You weasel-faced whoreson!

Wow, you call them ugly and insult their mother.

You know, I may use these occasionally. I doubt there are many who are quick enough to think up a comeback after these.