You pretty much know what you’re in for every summer when OzzFest rolls into Mansfield, as it did a week ago Tuesday for the first of a two-day stand. As I entered the gates midway through the first of the two 13-hour Tweeter Center metal marathons last week, body art and bad sunburns were apparent. And as always, the lines at the beer stands were long, longer, and longest, leaving the woman selling fruit smoothies all alone at her little booth. These are, after all, Ozzy’s people. And even if Ozzy no longer indulges, they’re still a few years away from rehabbing.

The most surprising element at this year’s event was the number of un-metal-looking collegiate types. The astounding success of Ozzy’s reality MTV show, The Osbournes, has obviously widened the former metal monster’s demographic. And his new converts appeared to be having the most fun — like children on a trip to the zoo, they wandered the grounds, happily taking in all the exotic sights and sounds. Ponds of vomit dotted the perimeter, adding to the ambiance.

Make no mistake, there were plenty of animals on board. As System of a Down threw down heavily loaded riffs of steel, the crowd tossed chunks of sod from the lawn area; these rained down onto the pavilion like mortar fire onto a battlefield. One man actually had to be taken away for medical care.

Why would anyone brave such a harrowing concert experience? For the headliner, of course. And what did Ozzy give us? He started with a long commercial for next year’s Osbourne series augmented by his own loud guffaws over the PA. Then he anointed the folks in the good seats — the ones close to the stage, that is, soaking everyone in the front three sections of the amphitheater. Ozzy even joined in the fun by pouring a bucket over himself. What might be a good gag on a sweltering night down South didn’t go over too well in New England as the mercury dipped below 70. By midway through the headlining set, a good portion of those who’d had the "best seats in the house" were shivering on the concourse like party guests who’d been thrown into the swimming pool.

The evening might still have been worth it if Ozzy had delivered something special. But he didn’t. The set was a predictable mix of hits and profanity that found his voice even shakier than usual. After all these years as a metal titan, Ozzy’s real place these days is doing unwitting comedy with his own Harriet — Sharon, that is — on the only show that’s up to bearing his name.