Seriously, what's wrong with this guy?

Matthew Clemmens, a 21-year-old from South Jersey, took boorish behavior at a sporting event to an all-time low at Wednesday's Phillies game at Citizens Bank Park, authorities said.

Police said that Clemmens shoved his fingers down his throat and vomited on the 11-year-old daughter of off-duty Easton Police Capt. Michael Vangelo, then slugged the cop in the head several times.

"It was the most vile, disgusting thing I've ever seen," said Vangelo, "and I've been a cop for 20 years."

The revolting display followed several innings' worth of slurred curses, spilled beer and spit that Clemmens and another man directed at Vangelo, his two daughters and one of their friends, said Philadelphia police spokesman Lt. Frank Vanore.

There was no motive known for the continuous harassment - except, perhaps, sheer stupidity.

"It reminds you of the type of behavior you used to hear about at the 700 level in Veterans Stadium," Vanore said.

Vangelo said yesterday that the trouble started "the minute we sat down at the game."

Clemmens and his cohort, who were seated a row behind Vangelo and his family, loudly cursed until his 15-year-old daughter asked them to stop.

Things quieted down for a little while. "They started back up," said Vangelo, 48. "One guy started spitting . . . first it landed on the back of my daughter's chair. Then it landed on her hooded sweatshirt."

The fed-up father kept his cool and reported the thuggish behavior to an usher. Security officials escorted Clemmens' pal - the spitter - out of the stadium.

Vangelo said that Clemmens then loudly stated that he was going to be sick. "He leaned over and put two fingers down his throat," he said.

Vangelo said he tried to hurry his kids away from their seats, but Clemmens "leaned forward and started vomiting on us."

Other fans - including another off-duty Easton cop - intervened when Clemmens started landing haymakers on Vangelo, who relied on otherworldly restraint during the assault.

"I kept thinking, 'If I get arrested, my kids will be alone here,' " he noted.

Vanore said that Clemmens ended up tussling with Philly police and "threw up on one officer."

Clemmens, of Cherry Hill, was charged with simple assault, aggravated assault, harassment, resisting arrest and related offenses.

"I was just a dad with my kids enjoying a game," Vangelo said. "I never experienced anything like that before."