The management of El Azteca was fed up with the vomit, the dining and dashing and the missing sombreros - all symptoms of having a drunken, college-age clientele.

So the famous -or perhaps notorious - margarita-making restaurant at 7th and Chestnut streets took action last December.

The result was a restrictive contract that every group of six or more now has to sign if its members want to enjoy the restaurant's atmosphere - for instance, clients now have to pay $50 if they throw up in the restaurant.

"A few people puked at the table last year, and one guy punched a hole in the wall of the bathroom," said Oscar Agular, a manager at El Azteca. College students "are pretty out of control when they start getting drunk. We needed to protect ourselves."

And El Azteca is not the only restaurant that utilizes such tactics in respond to its raucous income source.

Ajia, the self-described "Japanese-fusion" restaurant at 31st and Walnut streets, had multiple incidents with college students in its New York restaurants. All its locations now require that groups of six or more give both a credit-card number and a driver's license number before they sit down.

Las Cazuelas, a Mexican restaurant located in Northern Liberties, imposes far less-threatening policies on its patrons. The eatery only requires that its waiters call cabs for any drunk clients - many of whom are students.

Bistro La Baia, an Italian BYOB in Center City, simply warns its clients when they are getting out of hand.

Representatives at Las Cazuelas and Bistro La Baia say they have had few negative experiences with students, which likely accounts for their less stringent rules.

Meanwhile, El Azteca had more horror stories than all the other eateries combined.

"I once had to chase people down the street for not paying the bill," Agular said. "People started taking our sombreros off the wall; some people started to steal our pitchers."

As a result, one member of each group, designated the "group leader," must give his credit-card number to management and pledge that he will be responsible for his group's actions, that he is aware that underage drinking is illegal, and, of course, that he will fork up the money if anyone can't hold down their booze.

Finally, the birthday sombrero and ice-cream pie, once complementary, are no longer free.

And not everyone is happy about that.

"That's no fun. It's too bad you have to make a down payment to eat in a restaurant," said College senior Katie Duncan. "The whole point is the free sombrero."

Agular said El Azteca has not lost business as a result of the policy changes, and some see the rules as reasonable.

"Penn students in particular take things for granted. They go to this restaurant and don't think about the consequences of their actions," Wharton sophomore Dennie Zastrow. "It ruins the fun for everybody."