Every year around this time, another group of high school seniors takes a last stand for youth, with an act that captures the attention of the public -- and sometimes the police.

Pranks by the departing senior class can be funny and harmless, like the time someone loosed a pig in the hallway of Fulton County's North Springs Hall School. But sometimes they can be destructive, criminal even, like in 2006 when someone used a sledge hammer to destroy a $5,000 statue of a ram outside Grayson High School in Gwinnett.

The wisdom to know the difference is crucial, especially in this competitive age when a criminal charge can damage career prospects. .

Two dozen teenagers in Paulding County are now saddled with such worries after finding themselves before the local prosecutor this month. They had spray painted East Paulding High, some school vehicles and the entryway to a neighborhood.

District Attorney Dick Donovan said even the homeowners near the school asked him not seek prison for the youths. He gave the teens an offer aimed at ruining only their summer breaks: pre-trial diversion that would wipe away the felony vandalism charge in exchange for 400 hours of community service and $1,000 in fines and restitution.

"I knew right away I was not going to ruin anybody's life," Donovan said Monday. "It was just a matter of hoping they would recognize what I was offering, and that they would take me up on it."

They all accepted his offer, including the senior class president and potential valedictorian. Seniors had been painting a skull and crossbones in the intersection outside the school for about a decade, but this time they went too far, Donovan said.

But the line between serious and funny can be hard to draw, particularly for teenagers.

Consider Mike Fitzgerald. He was among a half dozen or so seniors caught outside Duluth High School after midnight one morning in the spring of 1995.

They had just finished digging two long trenches in the school yard, one in the shape of a nine and the other a five. They were about to fill them with concrete when an off-duty police officer hired to patrol the school came along.

They were charged with misdemeanor trespassing.

"Looking back on it, I realize it was stupid," said Fitzgerald, now 35. But at the time, it seemed like a rite of passage, another thing to check off the to-do list before graduation. "We were wrong and we learned the hard way," he said.

The charge was wiped from Fitzgerald's record when he pleaded no contest. He went on to college at MIT and now owns an Atlanta real estate brokerage.

Part of his motivation for digging those trenches, Fitzgerald said, was that adults, even faculty, had implied that senior pranks were acceptable. Teachers would wink and smile while telling stories of prior senior hijinks, he said.

"If somebody would have explained to me that you were going to jail," he said, "there's no way I would have done it."

Kenneth Trump, a consultant who has worked with metro Atlanta schools on security issues, said administrators should have frank discussions with seniors. They should explain that a criminal charge can make or break a job interview down the road.

"In today's world, where jobs are nonexistent, you don't need any negatives on your record," said Trump, president of National School and Security Services in Cleveland, Ohio.

Officials in DeKalb and Gwinnett say they warn students about the consequences of their acts. In Duluth, where Fitzgerald tried to immortalize the class of ‘95, local police send more patrols around the campuses during the last few weeks of school.

In Lawrenceville, Capt. Greg Vaughn said if kids damage a school, they can be charged with a felony, and the repairs can be expensive.

"They don’t understand that their mamas and daddies are going to have to pay," Vaughn said.

Seven years ago, seven teenagers were accused in a crime wave against the Sandy Springs Town Turtle art exhibit. A couple of the turtles, valued at as much as $5,000, were attacked with a hammer. Others went missing.

"They found one in a pond," said Lt. Steve Rose, of the Sandy Springs Police Department. "They said it was a high school prank, but it was a theft because those turtles weren't cheap." The kids were sentenced to community service.

The former juvenile detective said a fine line can divide a joke from a crime. For guidance, he said, teens should imagine how they'd feel if someone pulled their prank on them.

Rose remembered an incident some three decades ago, when kids let a pig loose in the hallway at North Springs High. Police got involved but brought no charges. That one apparently fell on the safe side of the line.

"The only people it upset were the school people," Rose recalled. "We thought it was kind of funny."

Staff writer Nancy Badertscher contributed to this article.