Gross, but somehow it wouldn't surprise me all that much considering he was shaking his ass in someguy's face in the front row, and doing the same with his crotch. By now he may very well be taking shits on stage.
I would carefully spray the mound with hairspray. Collect the now hard piece of shit in a ziplock and then sell it on ebay for an undeterminate amount of money.
He said that his most embarrassing or memorable (can't remember which) onstage moment was when he shit his pants while hitting a really high note. "Not a lot of shit, but enough to make you go 'oh, gross!'"
i'd laugh, and feel disgusted. well, depends whether he comes up walking with a toilet, puts it down, get his paper from under his armpit and have a proper crap. i'd laugh.