Guys, leave the little turdburglar be. He's feeding off your wish to put him in his place. Best thing you can to is make like he's not even there.
And then if he keeps it up, well, I'm sure someone will get a well deserved ding. The bar is high though, no lowbrow humor that he might understand. You know, like a brain that size what keeps your head inflated, or if I had ball like that I'd open a museum of miniatures and no mention of dimmest bulbs in the pack or sharpest marble in the sack, nothing of that crude, though understandable by our new troll, humor.
Have you noticed though, that when he does leave a thread, there's a scent much reminiscent of a fresh Summer's Eve...