“Mandatory” tipping was the main topic of conversation on the menu at restaurants across the city yesterday after word spread that a man had been arrested upstate for failing to leave a big enough tip.

“I think it was excessive to arrest the guy,” Massimo Stocchi, owner of Upper East Side Italian restaurant Mediterraneo, said. “But if the guy was trying to be an a-hole, I don’t know, I might have called the police.”

He paused to reflect. “I’m not really a ‘customer is always right’ guy. I work on the Upper East Side, where people tend to be a little bit snobby, but, really, when the customer complains, most of the time they are right, something is a little bit wrong.”

Long Island native Humberto Taveras, 41, was recently arrested for failing to leave the required 18% gratuity for parties of eight or more at Soprano’s Italian and American Grill in upstate Lake George.

He claimed the required gratuity was ludicrous, left just 10%, and stormed out of the restaurant. Owner Joe Soprano followed after him, informing Mr. Taveras the measly tip was unacceptable. Mr. Taveras yelled back, the police were summoned, and Mr. Taveras was arrested and charged with theft of services.

Prosecutors dropped the charges Tuesday, saying the wording on the menu made the tip a request, rather than a surcharge.

New York City law says restaurants can legally impose a mandatory service charge or gratuity for parties of eight or more people. The charge, though, cannot be more than 15% of the bill, and it must be conspicuously disclosed before the patron orders.

And what if a patron pulled a Taveras and refused to pay?

“Well,” said Chuck Hunt, the executive vice president of the New York State Restaurant Association, “I guess if the restaurant wanted, they could

call the police. The police probably wouldn’t be too happy. Probably a more sensible person would call 311 and be put through to consumer affairs.”

Mr. Hunt said he has received calls from restaurant owners, asking what they should do if customers refuse to pay the tip.

“The advice I always give is that you don’t want to win an argument and lose a customer,” he said. “If the customer objects to the service, tell them to leave whatever they want.”

Craig Hanson, general manager of Upper West Side restaurant Time Cafe, also errs on the side of the customer. “If a party leaves a small tip, we don’t ask them directly to pay it, but we’ll go over and ask whether everything was okay. We try to take care of it that way, rather than demanding people pay a certain percent,” he said.