Recently I was reading some detective fiction by John Sanford. One character said about a criminal : If he were any dumber we would have to water him twice a week. That insult has moved to the top of my list. Others I've been known to use are:

He's as dumb as a box of rocks.

He's a waste of oxygen.

He's a mouth breather.

He doesn't have the good sense to pour piss out of a boot.

He's from the shallow end of the gene pool.

And knowing that folks at the Mudcat have a talent for colorful language I thought you might want a chance to add to the list. You don't need to use them on each other. Let's just compile them for the good of mankind. I have an appointment at a bank next week and I may need some new fresh ideas. Thanks.